Here's the real problem:  Dude is engaging in 'scarcity thinking' and believes current woman in his life is the only woman who will ever be in his life and ergo, jealousy and possessiveness.  

Half the planet's population is female and while they may not all find you to be their cup of tea, a large portion of them might be interested so you have options.  Not one of them will be your current gal, but that seems to be likely a good thing.  One of them will come to you with open arms, leaving her baggage at the curb, and enjoy time with you more than her exes.  

The fact you are unhappy and the fact your gal wants to do stuff with her 'ex' is simply a nice clear indicator that you may want to open up your own options for happiness.  If you don't want to date someone who hangs with her exes then make that clear up front.  

This gal doesn't meet your needs but she doesn't deserve your misery either.  

You both may simply need other partners who accept you as your are.