Why is it so much easier for me to believe my ex

I know I'm an idiot and need to stop believing him. My ex/babies father has ruined my life. He lied to me our entire relationship. He has a criminal record on two different accounts of rape. First one was statutory rape of a 16 year old girl which his excuse was she lied about her age. I would have believed that had he not had the other charge for rape. This one was a male friend of his that he also faced charges and did time. His excuse for that one was there was a misunderstanding but never explained what that misunderstanding was. He later tried to sue that friend because the friend was HIV positive and he wasn't told which the case was thrown out for obvious reasons. If you get HIV from raping someone it's not the same as lying about having HIV but he claims he doesn't have HIV. I had been pregnant with his kid and the fact that he had been exposed to someone with HIV and didn't tell me made me wonder. I did dump him and went to get tested and I am also HIV positive. My son is HIV negative thank God. Me and him still coparent to some extent but he told me that he truly didn't know he was HIV positive and has been trying to convince me he didn't assault his friend and his friend lied about having HIV. Honestly everything he tells me can be disproven by looking at the court documents. Not to mention he plead guilty to both of these cases. But for some reason it's easier for me to believe him. It's easier for me to be mad at this former friend for giving him HIV that he then passed to me. It's easier to hate this stranger than it is to hate a man I had chosen to have a child with. Idk what's wrong with me and how I know he just lies toe but it's easier for me to just believe every lie he tells me no matter how easily it can be disproven. What's wrong with me😞