I don't think she can give her marriage a real chance or her family if she is still telling you she loves you. And i don't think you are giving yourself much of a chance because your head has been in an obsession cloud.
Now you are not clear... This guy is your best friend? (Talk about a betrayal.)
But you too, because he dated her knowing how you felt about her... But so did she. She knew you loved her so she goes with your best friend?
In the end i don't think you fully realize how dysfunctional this woman is. She is a married WOMAN. and she is not conducting herself as such. Sorry, i know you love her, but she is not all that and a bag of chips. If its a bad marriage she can leave...but she choses to stay and complain about it. Not very attractive to me.
About you and school. You should focus on you and college. Get a career and a future that YOU want and then you will find someone who wants the same. Right now i think she is trying to do the right thing for everyone.... letting you go. Please do what she wants for you. Its the right thing. It hurts, but in a few months it will hurt less, and in a year or so you will have your focus back. Good luck!