Impossible to get married

My boyfriend and I have been dating for almost 2 years. He decided to join the military which has made it really hard on us and our relationship. When I first met his mom she treated me good and seem not to have any problems with me. Once he left to training she started inviting me to eat and stuff, however as closer it got to the end of his training she started treated me badly. She would make rude comments on how she doesn't want me for him. When he came back he saw how bad it was but wouldn't do anything about it. I had to take it. (we have a long distance relationship due to the military.) I had to put an to threatening him with breaking up with him if he didn't do anything.He still didn't do anything until his mom got after him for not doing what she wanted him to do. She told him that I wasn't his family and he shouldn't hang out with me and that we weren't going to last. She told all her friend that too, and she said that my mom was a bad mother because she let me stay up to 3am one time (I am 20 yrs old). once he left again I was so sad, i cried a lot, and his family cant understand that I also love him and I miss him. I cry tons for him and I hate the fat that he is in the military. We both miss each other a lot and we want to get married, however I know that its going to be very difficult. My parents dont want me to get married till i finish college, and obviously his mom will never accept it. It gets me really depressed that i cant be with him, and i am the happiest with him. So my head is all over the place because his mom gives me a hard time and he just makes excuses for her, i dont know if going against my parents will be worth it, if he cant go against his mom. I just miss him and wan to be happy but everything seems to go against us.