I just don't know anymore

I don't really know where to start. It's a long story and I guess I'm looking into why I feel the way I do lately. I met my ex when I was 16, we were together for 20yrs. We have two kids, 20 and 16. Its been over two yrs now that we've been divorced. Our marriage was abusive at times, between us both, and I think he cheated once or twice throughout the yrs. I chose to look the other way but my gut tells me he did. I grew restless, bitter and resentful. I know he loved me the best he could, and the three yrs before I left was good to me. It was an ugly break on my part, with hurtful things said so he'd let me go. Once I was gone he immediately slept with girls he'd been in contact with though work, or myself, while we'd been married. Dispite my hurt over that, I freaked out over the loss of him in my life and wanted him back, we got back together for six months before I left again knowing the damage done, was worse then ever. Regardless we continued to sleep together even though we entered into new relationships. Im single now, breaking my last relationship off because I'm not ready and don't want to hurt anyone. My ex's current girlfriend found out we'd been sleeping together and chose to forgive him. He blamed it all on me, saying I planned and plotted in a sceme to get him back, even though he was the instigators 99% of the time. I know he feed her lies in order for her to forgive him and has cut me out of his life completely, to prove to her hes all her's. We no longer co parent and I don't agree that any relationship should come before your children and their parent, even divorced ones. Anyway... I'm glad hes happy but also upset that he can lie and cheat to get that way. He had no intentions of stopping what we were doing, only did so she wouldnt leave him. Im glad it's all out and we have stopped the vicouse cycle we were on, his girlfriend is a good lady and didn't deserve what we did, but now I feel I may never be happy. I feel so stupid for leaving, staying, and continuing what I knew was unhealthy for all involved. I feel I had love, and will never find it again at my age. I feel guilty that due to my choices our kids have parents who are dead to one another. I'm ashamed and embarrassed to express this whole thing to a professional who could help me get my head on straight. Any helpful feedback would be appreciated. Thank you

It is obvious from reading that message that he did not seem to want you as much as you wanted him. The reality is he liked have the piece(s) on the side. He could not even be faithful to his new girl. Take the emotion out and understand that he is not the answer. You will more than likely find that special someone without even having to look too hard. Do not be afraid. Try a reputable online dating service. Good luck!