Need advice for helping 5 year old cope with loss of father

Seven months ago, my son's father and I amicably separated. He was great about the whole thing, and made it very clear he wanted to continue to co-parent with me. In May, he found a new lady friend, whom he'd had a relationship with many years prior to us meeting, and suddenly his whole outlook changed.She was incredibly jealous of our life together. The marriage, the kids... And she told him that if he wanted to be with her, he needed to give us all up and start a family with her immediately----which included reversing a vasectomy.I didn't think much of it when he told me about it (we maintained very open communication), but a week after she'd given him the ultimatum, he informed me that he was done being a father and was signing over his rights and access to the children (S-5; D-3), and he'd chosen Aug 1 as the date for it to happen.I don't know what the hell was going through his mind, but he chose to tell my son that he was leaving to make a new family, and as promised, August 1st is the last time they saw their father.I have never seen heartbreak like this. I feel his pain so viscerally. He is acting out because of it, and despite weekly counseling, we've seen little improvement in his behavior. He gets angry and violent more often than not, and takes much of his aggression out on his sister.Life is hell with him around, and I'm struggling to help him and stay sane at the same time.Any suggestions or advice to help ease my baby's pain would be so so appreciated. I am at my wit's end, and desperately need this to end! via /r/Parenting http://ift.tt/2bytjK4