Andanotherthing I was once in your position, a long time ago. The marriage had it's problems, my H was unwilling to address them and the promise of a strong connection with a caring, loving female meant we parted. My DC were being affected by the tensions in the home, it was a bad patch in our marriage, and both of us were very unhappy, had no support, no one to talk to. No internet then for advice and warnings.
I was amazed that I had overwhelming feelings, and sexual feelings for a female, and quite confused looking back. I did the 'right' thing, the 'noble' thing. I wanted my H to meet someone who wouldn't turn his world upside down, who would be a better match, who could give him the chance of more children as he was 30. I was truthful, we agreed to part, it was civil, but very painful.
Me and female partner had a whale of a time, gave the DC a wonderful time, holidays, lots of fun, lots of new friends. It opened up their lives and gave them many experiences they wouldn't have otherwise have had. The marital home was sold, we bought a house together.
Me and H were still in contact, we were friends, he was very understanding, saw the DC each weekend...all amicable. But the divorce went through.
Then she left....for the next one, the next thrill, the next conquest. It had been a marvellous confidence boost for her... someone had [stupidly] left a marriage for her, 2 boys thought she was amazing and fun, and it all made her feel great. I was devastated, the DC very puzzled. It was hell...house to be sold, H met someone else etc.etc.
I didn't/don't deserve sympathy, I had been naïve, hurt my H who actually was a much more moral person than she was. The grass isn't greener, a bitter lesson was learnt and it was a huge, huge learning curve.
What I failed to realise was how people are capable of lying, of being so selfish, of not wanting commitment and of walking over other people to get what they want [excitement and novelty], even hurting children. I'd been in a family where no one behaved like this so it was a complete eye opener.
Single now, much, much older, living alone and never wanting a relationship again....no relationship since has worked out long term, just a long term [non-sexual] friendship. I have good relationships with my sons and grandsons but the past is a bit of an elephant in the room sometimes. [I'm sure it's the base of a problem between me and a DIL.] My sons are both in long happy marriages, are stable, hard working and well balanced men. All credit to them.
Would I do it again? Absolutely not. I was an idiot and didn't stop to think what her agenda with me/us was. So a cautionary tale. Make sure the calibre, moral compass and motives of the other person are sound and that you can put your future happiness in their hands. Or face the almighty mess that may ensue if not. Just my own story, if it helps or not.