Hi OP, I'm sorry you're going through this too.
I discovered my H's "midlife crisis" eight weeks ago. He had been having an emotional affair & exchanging sexual explicit WhatsApp messages with a colleague for about six weeks. His OW is also older than me - about 6 years. We had been together for 20 years and have 3 DCs together. Looking back, I did have a feeling that he was becoming detached, or drifting, from me last Autumn. We were still friends, still happy enough, but the spark had long gone from our marriage. There was no romance, no sex, no closeness, hand-holding, kissing etc. We had become more friendly co-parents than anything.
I found the messages one night. I had had suspicions about something going on with his phone as he had started taking it absolutely everywhere with him & had put a password on it. I naively assumed he was looking at porn on it - as this is something he had done in the past when things weren't great between us physically. Never did I suspect he would ever actually have an affair.
Since D-Day, he has been completely and utterly remorseful. He is almost like a different man - so kind, so caring & does everything he possibly can to reassure me that he's sorry and that he loves me and only me. He tells me that he never loved the OW, nor cared about her hugely, but was flattered and excited by the attention she gave him. Both were going through unhappy times/feeling neglected in their marriages (her DP is ill ) and casual chatting about life at work became flirting which became texting, which became sexting. The affair ended the moment I found the messages, eight weeks ago.
H is 41, 40 when the emotional affair started. Whether it actually was a one-off midlife crisis I can't say at this stage.
I still love him but I can't trust him and he has hurt me more than I ever thought possible. I threw him out eight weeks ago and he is still living with his mum.
I really don't know what will happen in the future. If I do take him back, will I forever be waiting for him to cheat again? Who knows?