HELP! ex boyfriend wants me back

my ex and and i broke up in march, after almost two years of being together when i found out he cheated on me with a girl he had been talking to for almost the whole time we had been together. i was sick and hurt for awhile and i've finally gotten over it.  the only thing is i allowed him to keep in contact with me. we text everyday. recently he's been asking if we can try again. that he's changed and back then he wasn't being himself. he claims that this is a whole new him and he will do anything to show me that he really would never do anything like that again. i told him i will never be able to trust him. & he simply said how can he show me he's changed and that i will be able to trust him again if i don't give it a chance. but i've given him multiple chances in the past and it led to him ultimately cheating. i love him and don't what a life without him but he said it's either now or never. he can't be just friends w me. i've also met someone new but he doesn't want a relationship right now but i don't want to stop talking to this new guy. so it's complicated on both sides of this. i don't want to be w my ex but i don't want him not in my life anymore bc he's like my best friend no matter what. what should i do?