Dealing with my Boyfrinds sons mom (THE EX)?

I think you are very mature over this considering you are only 20. The mother has problems and your guy seems to handle it very well indeed. I know it is not ideal, but you have him and he sounds very committed to you. Try and not let it bother you. She is bound to worry about her son more because of her illness, and try to understand this. I do not think she is trying to get her ex back. Little chance I am sure. It is just how she sees the world. I do not think there is another solution to how it is being handled, so as long as you do not have to deal with her try and relax. It will not be for ever and you sound happy enough otherwise. Take heart, you are young and healthy with everything going for you. She struggles through life. Sad really. Good luck.