New relationship, big issues, what do??

Details: 28f (me), 27m, dating 2 months. Throwaway acct. TL;DR at end.

So I met this guy online, and we instantly clicked, which was not normal for either of us. Especially me - I'm very socially awkward, shy, cynical, jaded, you name it. We are so alike in so many ways, and want so many of the same things in life. We have great communication, trust, an awesome sex life, and I feel so safe and comfortable with him.

However. We both acknowledged early on that we have issues. But it turns out that his are...a bit overwhelming. He was sexually molested by another boy when he was in elementary school. The abuse continued, undetected, for several years. Then in middle school he ended up molesting his younger brother. This was discovered, ruining many family relationships, but finally getting him some therapy for the rest of his childhood.

As an adult he has had problems with drug addiction (he is currently sober, only smokes trees). He views himself as a "monster" for all the things he did as a kid, and how that has led him to treat people as an adult - he says he ruins everything, hurts everyone, etc. He also says he is completely riddled with guilt. He says he is working, and has been working, on becoming a better person - and I completely believe him in that. I see his potential; I see what an awesome person he already is.

However however. It seems that these issues are far from dealt with, resolved, buried, what have you. Last night we had plans to go shopping, then to dinner and a movie. He went to his brother's house first to pick up a few things (different brother, and apparently unaware of afore-mentioned events) and this caused him tremendous guilt, sadness, and flashbacks. He started crying and we talked for a while, then he took a shower, assured me he was fine, and we headed out. At the mall he got super frustrated due to not finding his shoe size/width, and stormed out of the mall. He sat outside and cried some more, telling me to just leave him, he didn't deserve me, I should find someone else, etc. This lasted over an hour before he finally agreed to get back in the car, where it started all over again for another hour.

When he eventually calmed down, he apologized profusely and we discussed therapy. He agreed that it was pretty much necessary, and I got him an application for our state's low cost insurance program, as he is uninsured and only works part time.

I love him, and I thought this relationship had spectacular potential, but now I'm getting scared. I have no knowledge or experience dealing with anyone who has been abused. I don't know if this is something that therapy can actually help (I know he will have to work at it too) to the point where he can just be happy and healthy.

TL;DR: Bf of 2 months abused as kid, then abused another as kid. Fucked him up big time. He agrees to pursue therapy, but I don't know what sort of outcome to expect, how to support him...or if I should.