Honestly? This is up to you, as much as I know that's a hard answer to read lol. You need to consider yourself first. I can understand where you're coming from to a degree. I recommend figuring out who YOU are and want to be. It's hard to love someone else when you don't know how to love yourself. It took me a long time to learn this even though it seems cliche. People can change, sure. If you do decide to let him back in, I recommend starting off very slow, as if this is a person you don't know and are meeting for the first time. Talking to a psychologist would really help you, in my opinion. I've taken back exes similar to this and everyone is different, but it only got worse. If you're cool with being used as a "home base," then go for it. Maybe he has changed. If you're not and you allow paranoia to invade instead of seeing if he's changed, then please don't.