Why does he still want the baby if hes unhappy with me?

The situation: My ex isn't 100% positive our unborn baby is really his. I told him that there's a possibility it could be another guys. We were broken up at the time of conception. I was single and so was he. I slept with one of my guy friends as a spare of the moment type deal. I was still sleeping with my ex though. Got pregnant around the same time, and now Im at 39 weeks. The baby is almost here. My ex tells everyone he strongly dislikes me, Im such a bad person because of the history we've been through, theres not a chance in hell that we'll get back together, so on, so forth. He even told someone that if getting rid of me was as easy as saying it, then he would. You would think that he would hope the baby isn't his so that he wouldn't have to be stuck with me. Well, at least that's what I would think, you know? But he told me the other day that he's not gonna take a blood test and no matter what, he is still going to be a father to the child all his life. The other guy is more than willing to take care of his responsibilities if the baby turns out to be his, so this is not a case of my ex feeling bad for me because of a "deadbeat." The other guy is not a dead beat. He's been there for me this whole time and we've gotten along great. He was raised to be a man just like my ex and take care of responsibility. So, my questions are: 1.Would you take the same approach my ex is and want to be the childs father even if he wasnt yours, taking into consideration your hateful feelings toward the mother? 2. Why do you think he still wants the baby if it's such an ugly situation?