Should I help my son out in this situation? (Details inside.)

My son started a new middle school this year and one of his new friends invited him to a Super Bowl/birthday party this weekend. The boy is beside himself excited and I am really happy to see him making friends at his school. Here’s the rub: he is with his father this weekend. Whenever one of the kids has had an event on a weekend when they are with their dad, he promises to take them then comes up with an excuse at the last minute not to do it. After one too many very unhappy kids, my husband and I instituted a “No Planning Things with Friends on Weekends with Your Father” policy. Since this is late Sunday (only a couple hours before we would normally pick him up) and it is friends from his new school, we relented and let him attend.

There is a huge blizzard expected this weekend and there is no doubt in my mind that, although the snow is forecast to have stopped long before party time, his father will use it as an excuse not to take him to the party. Not going is really going to the party is really going to crush the boy.

So for the question. On the one hand, I want to tell my son to call me if his father refuses to take him so that I can pick him up and get him to his party. On the other hand I don’t want to bail out his father and have him (my ex) count on me to be the cavalry and save the day whenever he wants to flake out on something. I kind of want to protect the kid from seeing his father’s true colors, but it feels like that might be selling him a bad bill of goods. I kind of want to let him face the heartbreak, but that is tough for the mom in me to even consider.

What is your opinion, take him, or let his father devastate him?