I've been with this man for 7 years and I love him, however I just recently found out he's been cheating on his girlfriend with me.
What's your reason for loving and being with him?
My reason is that I wanted to feel less lonely
You weren't the party that decided to cheat so you aren't in the wrong here. You are allowed to date who ever you want to as long as the other party is willing. Sometimes relationships fall to form new ones and that's alright, but the guy needs to be honest and end things with his girlfriend.
I'm thinking about ending things. I don't want to hurt him, but I have to think about me.
While you aren't at fault, it's understandable that you want to end things as he lied to you too. I'd imaging you feel like he violated your trust. You should put yourself first and end things if you want.