I would let it go.
You're underwater on it and have no employment currently to make the payments yourself on it. Put the $ your boyfriend would have been spending on your payments aside each month. Buy a $1000-$1500 cash car with it when you go back to work. Establish a healthy emergency savings and get back on your feet from there.
BK is a chance to start over. Don't put yourself back on the hook for debt.
