A number of us have been where you are. Previous to RAH I was engaged and dating a psychotic sex addict. LOL!!!! Ok, so when he broke up with me I went through what you are going through right now......maybe a little different because I didn't really see the incompatibility that was there since the sex was so great and intense. BTW.....did I mention he had a wife and family 2 states away that he hadn't mentioned until I found out 6 months in? I literally thought i would never recover from this guy, and it was a much shorter relationship than 26 years. I spent 6 months trying to turn myself into what "I thought" he was looking for so he would come back. However, during that time too I naturally healed, and started working on getting myself in great shape (I'll admit the initial idea behind that was to entice the Nutcase, but I ended up getting way more out of it myself).
That's why I say what you are going through is very normal. For me yes I turned crazy. He didn't "make" me crazy per se. I put up with his unacceptable behavior yearning for a relationship that had no legs AT ALL. We had NOTHING in common. I had to forgive myself for all of it because I should have walked away with the first humongous lie, and I didn't.
Anyways, as a side note I had been long split from him (years) and ran into him. It was odd kind of to stand there and talk to someone whom I thought I couldn't breathe without at one point in my life, and he utterly repulsed me. He had gained weight (a lot) and gone really gray (Yay). his lower teeth were as crooked a dog d!ck (never noticed before). He had horrible taste in clothes and was STILL wearing a pair of shoes I had bought him I can't imagine how many times they had been resoled. All that is physical,l and I don't mean to sound shallow. I point it out because I saw him as the best looking man when we were together, and he was actually, stunningly, mediocre in looks. He talked about himself the entire time, he also did when we were together. Everything was about him. His issues, his work, his accomplishments, him him him him him. Nothing in common at all between the two of us.
You will work through this period I promise. Treat yourself well, do good things for yourself. Perspective will return.
Trust me one day you will talk to your Ex and wonder what the hell you ever saw in him.