Heartbrkn,
In the end it is your decision what you decide to do and only you know if you will be able to live with always having a doubt in your mind. I never got a chance to get that far. My exab left before I even realized he had an addiction. Even after he went to jail he said he after promising me he was going to change he said he knew I would never be able to trust him. Hes right. I couldn't even imagine living that way.
Everytime he's not with me I would question what he is doing. And to be ready if he does relapse if I could deal with it. Especially having a newborn baby. I do think when he left he did me a favor and it was a blessing in disguise.
But I know people who have stuck by their significant other who overcame their addicition and was able to work out their issues. I know it's possible but in the end it's your choice. Good luck with whatever choice you make.