Yes this young guy sounds deeply confused. Both of you are young and have a lot of life to live. Unfortunately, this religion tends to "keep people down" and "small minded" I have known a lot of stories like this (not me personally). Over the years, I've probably known around ten or so similar cases (give or take). Some were high school guys I've known that had a "worldly" girlfriend (I've always hated that term "worldly"). A couple of the guys got the girl pregnant and that's how they get there "secret" exposed, so to speak. This is a tricky thing too. Although your boyfriend probably really does care a lot for you and wants to marry you, I'm sure he really means that because witnesses young adults tend to take dating seriously which leads to marriage. But I am hoping that you have already met his family...? I assume you haven't. If it was me, I would show him this website because it will let him know that he is not alone and that a lot of people left the religion successfully. Of course, he has to realize that he will get a lot of pressure from his parents and the organization, but it does fade over time. This young guy does not sound strong. He's definately playing both sides. The best thing for him to do is to move out and rent what he can afford (even if it's renting a bedroom from someone - outside the cult).
To me, and this is what I did. I changed my phone number and moved. He doesn't have to go talk to the elders about what he did. I would walk away quietly as possible. (Although every so often my mother sends the elders to my home - I just don't talk to them, I look out the window. lol.) If he DOES speak to them about EVERYTHING...he's only causing more problems and a possible disfellowshiping. Which means, he's shuned and his own parents/family won't even talk to him. Over time, he will see he made the right decision and laugh about how "controlled" he was. It's kind of sad that he put you in this situation, if he's a man, he will own up to it and do a little self discovery. Whatever his decision will be, it would be his decision (not something that you pressured him to do). I can't believe that he "feels" that he owes people anything! Yes, it was nice that people in the organization supported the family when his brother passed away but he doesn't owe anything to them. That right there, tells me it's time for him to move on and get a quick construction job and move out. I really feel bad for him and you and hope that everything will work out well for both of you.
For me, I love celebrating the holidays. It's so much fun..especially halloween. I'm 38 years old and I get dressed up every year. lol. I never had any holidays growing up. Hang in there.