Should I take another chance with my sex addict boyfriend?

Throughout the year and a half we've been together, I have (on about 8-10 different occasions) found out he has been:

-Sending naked pictures to women on email
-Talking to his ex girlfriends saying he misses them and how hot they are
-Paid hundreds of dollars on cam-girl sex websites
-Contacted people on dating websites/craigslist for sex whilst on business trips

He is adamant it is an addiction problem. I'm finding it hard to get over... I love him so much and this is literally the only problem we have in our relationship. If it wasn't for this we'd be completely perfect and happy.

Last time I caught him doing this he promised he would get help and talk to me about it if he felt the urge. He went to a sex addicts anonymous meeting twice and then said he was fine. Then a few months later I caught him trying to get a girl to f**k whilst away on business. He even got another computer to sneak around on so I wouldn't know.

I'm completely torn and heartbroken.. He says he can't explain why he does it and has booked to see a therapist.

I really thought this guy was the one, but I don't know how to move on from being so hurt.. Help please? :(