First of all, life hardly ever turns out the way we thought. How boring it would be if it did!
Secondly, it isn't useful to look at this as failure. You haven't failed anything. You have been given some tough circumstances which have forced some tough decisions. And, it sounds like some more tough decisions still await you.
Third, his comment is abusive, manipulative, self-serving bs. He knows this is one of your soft spots, so that's where he goes with the sharp stick. I would venture that maybe even his suggestion to separate is really more about "getting you back in line" than it is about really separating.
It hurts. Yes it does. It's difficult, and that's putting it mildly. I know it doesn't seem like it right now, but the more you can accept the reality of what is, and stay out of the magical thinking of what it "could be," the better. The longer you cling to the reality that exists only in your mind, the longer you will be in pain.
I've heard it compared to ripping off the bandaid vs. slowly pulling at it one hair at a time. It hurts a lot to pull it off quickly, but the pain is over sooner.
Whatever you decide to do, please take good care of yourself. If you don't, who will?
L