It's possible that it could all work out, but it's not going to be easy.
The big question is, does he believe this religion is the truth or not? This is a cult, plain and simple, they use mind control to manipulate people, it's a hard thing to overcome. If he has researched this religion and doesn't believe it's "The Truth", and is only going back for his mom that would be one thing. But if he is just having a detour, engaging in conduct he believes to be wrong out of weakness, then the outlook for the future is not good for the both of you. Very often young JWs will have a rebellion, but later go back out of guilt, because they never understood how much they had been manipulated, and still think this is the one true religion. Of course he would never believe or accept that it is a cult, that is the nature of cults.
I would hate for you to invest a lot of time in a relationship only to be disappointed when he decides to marry a JW. Even if you got married, the JW life is to be quite involved in the preaching work, hours of meetings every week and lots of study. Are you prepared if he decides to embrace that life? What if you had children, are you OK with them going to the Kingdom Hall on a regular basis? How would you feel if your husband taught them that you will be destroyed at Armageddon because you were not a JW? This is what they actually believe. You have seen for yourself the awful practice of shunning, is that what you want in your life? I have seen hundreds of families torn apart by this, including my own, it's not pretty.
If I were you I would ask your boyfriend to do some research on the history of his religion. Most Jehovah's Witnesses have been taught to fear anything written by former members, we are considered "mentally diseased apostates". It's a sort of phobia, the fear makes them reject anything we say, that's why it's so hard to get them to mentally break free. But if he is willing to look into it you might have a chance. I suggest JWfacts.com as a start, or to read the book "crisis of conscience". If he refuses to consider "apostate" sites, then it's going to be harder, but you could suggest he research some of the main teachings from a neutral source. He could research early leaders like Charles Russel, or Rutherford on Wikipedia, do a search on sex abuse and Jehovah's Witnesses or the Australian Commission and Jehovah's Witnesses. Also, have him research one of the churches main teachings, which is the end times chronology based on the fall of Jerusalem in 607 (hint, it didn't actually fall in 607). If you are willing to do some research, I suggest "Combatting Cult Mind Control" by Steve Hassan. He has good info on how to help someone in someone in a cult to break free.
Good luck.