Hi... I was in an abusive marriage for 12 years... when you describe your feelings.. it is like a "flashback in time" for me.. So I guess what I saying is that I feel that your relationship with your boyfriend is/was abusive... And a part of that for me was the "guilt" of leaving.. a terrible feeling ... that is hard to put words to... low self esteem for sure..
I felt that I had so "lost who I was" that I didn't have enough substance to cast a shadow. I was the one seeking to get the divorce... yet I felt so bad.. like I was chopping off one of my limbs - very graphic.. but I think a Therapist described it to me as - that I was literally leaving a whole lifestyle that I had grew acustom to.. for the unknown.. it had more to do with that... than the actual man..
I was choosing to live for me.. uncharted territory.. scary.. the marriage abusive as it was.. at least I knew "what to expect".

Trying to prove that you are a "good, loyal, nice" person to this man... will never work...... because he has the mindset - that won't allow him to "see" that and reflect it back to you.
That is what abusive men do.. at least my ex-husband.
I felt very simliar to what you are describing... as soon as that was explained to me - that I could never accomplish this goal... I gave up and moved on.. to a new life..