Although I don't know enough to tell you the underlying causes of his behavior, there is one major theme that should explain. Sadly, this sounds like a man who, for some reason, has learn that in order to be loved he must also be abused.
This is common in people who were abused by their parents as a child. The child learns that the parent, who loves & takes care of them, also is the one who scolds & beats them. They indirectly learn that love & abuse must go hand in hand.
That's why people who have been abused end in up abusive relationships. Even if he wasn't abused as a child, if he had an abusive wife for 30 years...that would be enough to also explain this.
The next question is why did
he stay with her that long...which is likely a long & complicated answer that cannot be answered without talking to him. It's hard to leave a a marriage...after all it's "till death do us part." Some people are also afraid to start over with someone new ("what if this is as good as it gets & the next person is worse") or afraid to be alone.
I understand that your self-esteem feels low at the moment, but likely his is worse. I don't want to guess to much, but one possibility (and there are numerous) is that he freaked out after even a couple arguments with you thinking things might get worse. Or maybe he is so down on himself that he doesn't think he deserves you. Keep in mind, that his subsconscious is likely influencing him so it's possible that he doesn't even realize all the reasons he went back to this abusive woman.
The obvious part here is that it's not your fault. All couples have arguments, so don't get too hung up on the ones you had with him. It might not hurt to try to reach out to him romantically and give it one last shot...but be prepared for the worst case scenario that he conintues to self-sabotage (consciously or subconsciously) and stays with the other abusive woman. If so, move on as best you can...life is too short & you deserve to be happy & live it to the fullest.
I hope this helps. Let me know if you need more feedback. Good luck & take care.
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