am i wrong??

so me and my SO been having problem for quite a while now (fighting, no intimacy, etc) well one of my exs recently separated from his and decided to contact me. we started to catch, asked eachother about our kids and family. then he drops the bomb that he still and always had feelings for me even tho he was married to someone else (when we dated we were both youn g and stupid and didnt know what a real relationship was) and im not gonna lie...ive always kinda carried a torch for the guy but had to move on. ive been. with my SO for going on 4 years hes cheated on me multiple times, has layed his hands on me (both of these happened more than a year ago and haven't happened since) he lies to me about the pettyest stuff, hides money from me ...always up his parents ass and chooses them over me and our son constantly talks about sex, always pointing out whats wrong and things im not doing righy. but since ive started talking to my ex (he tells me all the things my SO doesnt like that im beautiful and all tgat giid stuff) and when he tells ne all these things it somehow magically turns my sex drive on high and i end up having crazy sex with my SO and even tho its sounds crazy its actually helped our relationship. i know its wrong to be talking to an ex but it couldnt be that bad if it helps my relationship can it? i pretty much need someone to tell me im a horrible persin for doing this because i fill guilty for talking to my ex but it makes me happy because its brought intimacy back between me and my SO