I hate to say this, but I would keep my guard up. My husband was clean and sober for 15 years when we first got together. He relapsed a couple months after we got married and has been in active addiction for the last 4 years now. He's had bouts of sobriety but has kept going back out over and over again. Each time he got clean, I supported him, cheered him on and celebrated each milestone with him to no avail. I was still always in a knot waiting for the other shoe to drop and find out he was back using again. You have to draw your line in the sand and don't let him bully you or guilt you into moving the line further and further back. Figure how exactly how much you are willing to stand and make that clear to him. Good luck to you!
Tracy