More Disenchantment; plus I'm an idiot

I called him today to thank him for watching our house while we were gone. He sounded happy to hear from me but the conversation quickly degenerated from there. He told me the girl at the kennel was good-looking. He dissed everything I had to say about hiccup cures, and not gently either. He criticized my daughter's friend and the way he stays over at our house; said D and I have some serious boundary issues there. I hung up vowing yet again to stop seeing him. All the way home I pep-talked myself about not seeing him again. Then there he was in his red Saab, turning onto our street at the same time as me. He pulled over, I pulled up next to him, he said he felt awful and would I come over and nurse him. Sure, I said, while thinking "What am I doing? Why can't I just cut this off?" He really did feel awful, even threw up several times while I was there. We squeezed in some sex in between dashes to the bathroom. Do you think he's just using me? (said sarcastically). I've mentioned before that he doesn't work very hard at this relationship. I am acting like a silly, stupid and inexperienced young girl willing to throw away everything for some worthless guy. I see myself doing it and yet I can't stop.