Why would you WANT to stay with him?
You say you've already been through previous relationships with lying cheating and said you didn't want it any more.
- Yet, he is lying.
- Yet, he is cheating.
- Yet, he is visiting professional prostitutes.
- He is a recovering addict.
Cut your losses at the 2year mark, or continue to wonder, worry, obsess, fear for your health, fear getting dumped, fear a relapse of his drug usage, etc.
What is he going to say about this that will make it okay? That he's SORRY? That he didn't MEAN for it to happen? That he was drunk? That it was his friend's idea? That it will never happen again? That it meant NOTHING?
What did he tell you THE LAST TIME you caught him lying? What did he tell you the last time you had struggles regarding his addiction?
It's entirely UP TO YOU! If YOU believe you are worth more than the bad behavior in this relationship, then LET HIM GO.
TELL HIM WHY. MOVE ON PERMANENTLY.
YOU can't fix him; only HE can 'fix' himself...and only if he WANTS to.
You can only fix YOU. Get some Individualized Counseling and figure out WHY you're involved with a former drug addict who lies to you and cheats on you. If you don't fix yourself, your next relationship will be NO BETTER than this one, or the last one, or the one before that.
PS: I'm going to notify a moderator that your post is in the wrong area of TAM. You're in a section where the moderators usually post INSTRUCTIONS/RULES for the website.
One of the moderators will move your thread to an appropriate board where MANY MORE people will be able to give you advice. The moderator will let you know where to find your thread!