Show him that you are fearless. You've been folding after every thing that he's done to you. I think that would be a good time for you to take a stand.
Keep it strictly for the kids and family. You are there to see them. Not him. Hang out with his relatives but most importantly, do not talk about the R to them. Just try and have as good a time as you possibly can.
So, go and allow the kids to have a good time but avoid him as much as I can.
Me: 33 / H: 36 M: 10y / T: 14y 3 kids BD: 2/22/14 Live in separation 3/8/14 H consult lawyer, says filing asap 4/24/14 H moved out 4/25/14 2nd time around. 1st separation 4y ago lasted a month
