Did you ever give him a letter,

"I know we may not be able to salvage...but I hope...either way, I want to say in writing that I was very hard on you...in therapy I realized that I was afraid of losing you....pushed you away...can get why you don't want to come back...hope you do for us, not just for your son or daughter...but if you don't...I want to make my sincere apology for not being there when you needed...and hurting you deeply because of my own hurt and fear...