I don't know what to do..

I have a boyfriend that I've been with for a year already. I've been the most happiest person alive but I just recently found out something that he was doing. I found out he was talking to another girl very sexually, telling her he wanted to go and see her and do crazy things to her. I got upset and started to cry. I didn't know how to approach him at first and one day it just came out... It hurt me a lot because I haven't been in a relationship in a long time after me and my ex broke up. When I got with this dude it was like I was starting all over again. Should I just walk away from the relationship... I can't get out of my mind that he was going to end up doing that to me,or should I make it work with me?