You're very kind, OP, and shouldn't regret your first impulse. Just give money one time and feel good about it. Then in the future you can suggest to your ex ways for them to cut expenses.
I don't think you should judge them too quickly anyway. They moved already, and it must be very hard for them to downsize their lifestyle. We've lived on 100K as a family of 4, but we were earning less before that, so of course we made it work! They're doing the opposite and for them it's a steep learning curve.