No reason you STBX-BIL needs to be involved with your kids. Your sister probably wouldn't appreciate it and it is a consequence of bil's decision to leave your sister.

My nephews went from having 2 uncles to none due to divorce and death. Not the ideal but they have dealt with it fine.

Just break the news to them in a straightforward manner "aunt X and uncle Y will be divorcing and will no longer live together. Therefore we won't be seeing uncle X at our visits". Then follow up with them to see if they have questions

I think you are overthinking it. If you don't freak out about it, your kid is not likely to either - they might be a little upset at first, but that's life. I would not go out of my way to see BIL, though if he asked to see the kids I probably wouldn't be opposed.

Long story short, my sister and her husband are divorcing. They have a 4 year-old son and they live about 2 hours away from us. I take my 2 kids (DD 6 and DS 8) to visit every couple of months or they come see us here. My 8 year-old DS has always loved my sister's husband, mostly b/c he is a big kid and enjoys playing with my son. Neither my husband, nor myself have ever liked him much, but we have always tolerated him b/c a. he is my sister's husband, and b. my kids love him.

So now I am finding it hard to figure out what to tell my son. I don't see how he will maintain a relationship with my BIL now that they are divorcing. BIL has chosen to leave my sister and the whole thing is pretty awful, she is devastated, their 4 year-old is a mess, etc. I'm just at a loss b/c it feels wrong to say "Aunt Jenny and Uncle Joey are getting divorced and so you won't be seeing Uncle Joey anymore". But I can't see myself making a trip 2 hours away to have DS spend time with his uncle who none of us can stand, now that my sister isn't even in the equation.

Has anyone ever been through anything like this? Any thoughts? Advice? Obviously my kids will continue to enjoy visits with their cousin- that goes without saying.