Unless he researches wts' past and realizes that he's in a cult and needs to get out and adjust to real world, your best option is to move on with your life. It may be very difficult thing to do but DO NOT GET ATTACHED TO A CULT MEMBER.
If you marry him, you will be the black sheep in his family who may or may not treat you like family member until you actually start showing interest in their beliefs and get baptized. Basically you won't have a real family! When you have a serious relationship with someone you usually join both families together and that just won't happen by marrying a witness. Holidays will all be evil so you may end up fighting over those, if you have kids, he will want them to be JWs which puts them at risk of being restricted to what medical treatments they will get and higher education will not be in their cards.
If he does realize he is in a cult and leaves, he will be shunned by his entire family, your kids won't know their family on his side, or if they do, his family will try to influence your kids.
Their doctrines are always changing so you don't have an idea what radical changes can take place tomorrow and to what extend will your "future" husband follow them.
As you began to study with them, just keep in mind
- they misquote others, so you be careful of agreeing with what their publication say
- JWs don't know their real history as they depend on what they're told about their past in present publications which also whitewash their past
- they will befriend you as long as you study and progress, the day you drop interest in studying with them they and all those friendly with you will also drop you as their association
- they will try to avoid your real concerns or questions so make sure you have your concerns and questions fully answered to your satisfaction and don't go on until they answer your concerns/question
Unless he researches wts' past and realizes that he's in a cult and needs to get out and adjust to real world, your best option is to move on with your life. It may be very difficult thing to do but DO NOT GET ATTACHED TO A CULT MEMBER.
ps: This is general description of JWs but he and his family may be one of the very few who are different, but what are the chances of that. Read and learn about the group because you don't want to put yourself in an disadvantaged relationship that you will regret months after marriage.