My boyfriend hid his addiction...

So I just found out over the weekend that my boyfriend has had a pill addiction for years and he’s been on suboxone for the past couple of years (illegally) and he’s hid this the whole time we’ve been together which is about a year and a half. Granted I always knew something was off with him I just could never put my finger on it - he was always moody and could be mean and just seemed out of it. He told me he’s kept himself on a low dose for years to avoid withdrawing and he doesn’t get high. Well since I found out he threw out all his pills and is currently detoxing right now and wants me to stick by him. I do care about him but I feel so betrayed and deceived and like I’ve been with a stranger this entire time. I should also add that I have a child who’s father died of an overdose and he knows all of this. I made a promise to myself to never be with an addict again. I just don’t know where to go from here. Should I stay or should I walk? Thoughts?