Well, sniff, I reckon by now most of us have the tee-shirt but I'm know this doesn't make things any easier. Sorry to read that you are going thru this.
If there's anything positive to say it would be that you are not ried up with someone who isn't your soul mate. That's okay 'cause I just have this feeling that we all do have a soul mate, someone to grow old with, someone to validate our lives and life is too short to get bogged down with someone who isn't that person.
Plus, with the age difference, heck, you now don't have to look forward to pushing this imposter around ina wheel chair while yer still very much in life's game.