Based on what you described, your boss might have unreasonably taken out on you something not of your making. But be a peacemaker, and offer an olive branch to the extent that it does not put an unbearable burden on yourself. Your new career is just beginning; if you can somehow craft a win-win solution to the current dilemma, you might reap some handsome benefits down the road from a little sacrifice now - consider the latter as a downpayment on future goodwill.
If worse comes to worst, simply walk away, with a sense of pride and accomplishment. After all, what has come to past is now behind you. Focus on the future, not the past.