Regretting Love: How to Move On?

I'm sorry. What happened?

I'm in a very similar boat. I gave him my life, and 2 kids. He goes behind my back and cheats. Now I'm a single mom to 3 kids.( I have my oldest from a previous relationship.) And my ex claimed that he didn't love her, but he still goes to see her, and tell her and all of his friends lies about me. He told them that I threatened that he'd never see his kids again if he didn't leave her, and do exactly as I said. ( All crap. I asked him if he wanted her instead, he said no, and begged me not to leave him. Crying the whole time.) Point is, I'm here if you need to talk.