before you can be happy for two people you have to be happy for one. sounds like she won't even allow enough space for that to happen.you can't get balance when constantly wondering good time/bad time, speaking/not speaking? etc.

never mind what I think of her needs, to be engaged to marry someone I would want to know that I am in it 100%..but you can't even ask your family, or even just speak to them because she won't let you.

personally I would run far & fast. her train is going to crash hard & fast, and there are goin g to be lots of casualties. and oif you are connected then it will be "your" fault. no one needs that. run. your grades are at risk and what if she doesn't like your career or if god forbid you get an offer far away? will she travel with you? or not? how ugly will that be? will she un-marry you at every disagreement?

get out while it's cheap & easy.