Don't worry about how she is going to handle a breakup... that's her business. Your business is to look out for your own best interests while being straight forward and with compassion towards her.
You simply tell her that you have discovered that you do not have enough in common to go forward and therefore you are not going to continue on in a relationship that you know will never last a LIFE time.
Then you wish her well and you go zero contact. You are naturally fearing hurting her (most people who are not sociopathic would be but you cannot let how she is going to react to your decision make you abandon what is ultimately in your best interests.
You are not being abused. That rhetoric is coming from someone who is projecting her past life onto you so don't worry about that. Therapy however is never a bad idea if you're having a hard time with being able to say "no" to people and therefore allowing them to take advantage of your good nature.
Let us now how it goes when you have the break up talk with her.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion