Honestly, if the bugger is mean and you know it, I wouldn't have my kids there without me. If I'm not exposing my kids to abuse in my home I'm certainly not doing it elsewhere.

Sorry this happened. It's one of the reasons I wouldn't have my dad babysit- he was a good dad but has a quick temper and his years away from kids has made him think they practically are out of diapers, talking, emotionless and making their own coffee at 18 months old.

OP here. Thanks so much for your advice, everyone. I did talk along those lines on the ride home...basically, I just said that some people communicate differently, that new marriages can be tough and they're probably still working out some of the kinks, etc...but I didn't really believe anything I was telling him. Like I said, my dad can be really mean and without hearing any details, I could picture the whole thing in my head. I just really hoped that he had matured a little or would at least TRY not to start fights in front of his grandson on the one night he was over.

As for the previous poster, I like that idea but I'm worried that if my father's wife isn't around and it's just my son, he might be the next target. I made it a point to never be alone with my dad for too long when I was younger because he just can't seem to control his mean comments. I had hopes for my son because the two of them seemed to bond in a way that I never did with him...but I don't know if I want to put my son in that position. It's always something really small that sets him off...and no, it doesn't help to know that something much bigger is probably bothering him.

Does anyone else have, like...mean parents? How do you navigate your relationships with them and their relationships with your children?

I would use it as a teachable moment to talk about how sometimes people have relationships that bring out the worst in them, and that it seems like Grandpa and StepGrandma have that kind of a relationship. That you think it's sad and you wouldn't want to be in that kind of a relationship or want that kind of relationship for him, but that it doesn't mean that his relationship with Grandpa needs to end -- that he can still have a relationship with Grandpa, and they can still go fishing (or whatever) together, if that's something where Grandpa and he can have a nice time together, if he wants to do that.
But agree no more overnights.

I had one set of loving, warm grandparents. I had one set who used to fight in their native tongue, who were stern and critical and light on affection.

As a child, clearly I preferred the warm grandparents to the stern ones. But as an adult, I see the wonderful value they both brought to my life. I also have the perspective to know that my stern grandparents had VERY hard lives, so yeah, of course they were a bit hard.

Maybe don't arrange overnights, since it doesn't like a fun thing to do. But I wouldn't go crazy limiting their time together. Just keep outings shorter and focused on your son.

Hope your dad isn't going to trade this wife for an even younger version. Yikes.

I know you are crushed for your DS but some of that may be you projecting your own emotions from childhood on him.
Remember - his dad isn't a primary caretaker. Your DS is growing up in your household, in your care, and is experiencing a very different childhood than you did.
The stakes aren't as high for him - he was upset and wanted to leave, but it won't necessarily be damaging to him because now he gets to go home to a place where he doesn't experience that kind of conflict and discomfort in a daily basis.

I would just talk to him about his experience - help him sort it out and be a sounding board by validating and supporting his feelings about what he saw. Because he is raised by you, he is able to recognize the behavior as mean and something that makes him uncomfortable, and that's a good thing.

Good chance to talk with your son about how people behave differently and you're bummed he didn't have a good time. Leave it at that.

I wouldn't say much to your dad unless he asks. If he asks to have your son again then you can be honest that your son would rather not stay again so so because he felt uncomfortable with the dynamics in his house. If he balks just point out that you and your DH don't argue in front of him so he's not used to it and was upset.

I think maybe take your son's lead at the moment. If he doesn't want to spend time around them, then distance yourself for now and only say something if you really want to. If he'd like to continue to spend time with your dad, then you do have to say something.

My parents bicker a lot, though they mostly keep it under control around their grandchildren. I have made it clear in the past that if they can't act civilly around us (either me or my kids), then they'll see a lot less of us. I don't know if they would ever be capable of communicating without arguing, but they know not to do it around me. When I was younger (20s) they told me that I couldn't tell them how to behave but at this point they've recognized that when they argue I stop spending any time with them.

OP, a couple thoughts:

This could be their "normal", i.e., they bicker all the time and it wasn't them acting badly, this is them. They may not even be aware of it, it could just be their baseline if you will.

If you and your husband don't act like this, it would be a shocker, yes, for your son, which is a good thing.

I think you should deal with your son, talk about why it bothered him, how you feel badly that this is how your dad and wife communicate, why we don't talk like this, how we don't hurt people with our words, etc.

The only way I would bring this up with your dad is if your son doesn't want to go back. Then if the invite is extended, you say that your son was upset at all the bickering and doesn't want to go back. And see how he responds.

If this is their normal, he'll say he has no idea, make excuses, blame your son for being sensitive, whatever.

If this was a one off, he will be mortified and profusely apologize.

My advice would be different if you were close, then you could talk to him, but if you are already strained and not close, and these visits aren't usually happening, then I wouldn't bother.
My guess is that this is how they are and a conversation would be futile.

Spend your energy using this as a learning experience and life lesson kind of thing for your son.

Recently, I've been trying to spend more time with my dad. I've never been very close with him...I find him condescending and even a little immature (his new wife is my exact age). But I admit that he and my 9-yr-old son seemed to develop a nice little bond. DS looks up to him and they get along so I've been putting more effort into making plans and so we can all get to know each other better. Like I said, it hasn't been very easy for me but I felt like it was important for my son to know his family.

All was going fine until...DS asked to spend the night over there last weekend. Dad and my stepmom both enthusiastically agreed to have him so I said okay.

But when I picked him up the next morning, he looked upset and really wanted to leave. As we drove away, DS basically said he spent the whole time watching and listening to the two of them argue. He said the littlest thing would trigger terrible comments to each other and he was so uncomfortable. He also said he thinks my dad is mean now. I was so crushed for him.

I'm mad at myself for trusting my dad (he was always like that) but also just mad that the two of them would put a little kid through that. They couldn't behave for a few hours while he was visiting?

Do I just let this go and distance myself? Or do I need to say something?