Yes. I went through the classic midlife crisis.
Blaming me, changing overnight, monstrifying me, re-writing history, manipulation. I honestly look back on that first year and don't know how I didn't jump in front of a train. It was the most confusing and painful experience of my life and my lovely DH seemed to not even remotely care about what he was doing to me. Weeks before we'd renewed our vows. It was like being hit with a sledgehammer.
He was with her for only two months, and although he regretted it a bit then he felt he'd badmouthed me to his family and friends and there was no way back to he tried to get on with it.
18 months after it began, he showed up at my door. He told me I was the only person who'd truly loved him in his life and that we'd had a fantastic marriage. He told me for whatever reason he had been deeply unhappy in his life and thought it was me an it took a long time to realise that it wasn't and he'd made the wrong choice.
I had deeply loved him and our marriage was great. Being honest, I never stopped missing him (still do) and tears still drop out of my eyes even though I have a lovely new DP and have moved on.
Fact is though, regardless of how much I love him, he caused too much pain to me and DCs and if I took him back he'd not be that same man who I'd loved and trusted so much.
I think you can forgive and forget affairs, but it depends on the manner which they treated you. If they came to you crying, saying sorry with remorse and honesty that's one thing - but for the men who follow the midlife script then getting past that extreme emotional abuse is very hard.
My ex is still alone, still depressed and he ultimately ruined his whole life. I feel a lot of sympathy, but he broke us.