Focus on you and your relationship with your son - if your fiance is bad news i would remove them from the picture now before it gets more complicated. I know it's rarely as cut and dry as that but your son is becoming a young man and i can't help but feel you need to get a good handle on his behaviour as well as your own issues before the consequences become harder to deal with. I hope you find a resolution to your difficulties - someone mentioned therapy which could be useful but what about more mother and son days? These don't have to be anything spectacular or costly, just a set period of time where you can both spend good quality time with each other. It also gives you an opportunity to lay down the law and reset any boundaries he's over crossed. All the best to you.