How to get over my ex?

I was with him for 7years and well he got into a relationship a little after we broke up like a month bc supposedly i had cheated on him, then he comes looking for me to saying i know you didn't cheat on me but you texed this guy. SO i got mad i need time and i don't know what to do? The girl he got with is well a h** she sleeps with girls and guys. I guess its an open relationship. I went thur his email and found this out. Now he keeps calling me and texing me and telling me how he misses me but its hard" wtf? we have been seeing each other,dating and well having . But now i am starting to think his just all talk. I mean he acts like were still together but is still seeing this girl. I have tried being understanding about the hole thing and well am tired already. I do still love him and want to be with him and i don't know what to do anymore. Should i keep seeing him? hoping he still wants to get back and maybe there is a chance? or should i move on? and if so how can i cut him lose?