Marriage nearly over, guilty, do I end affair?

[procrastinating50]

I am a guy in my late 50's and am in turmoil
We have been married over 20 yrs and reasonably happy for 15 yrs
(2 children now in 20's)

I loved my wife dearly and still care about her and find her very attractive.
I discovered she was having an emotional (& possibly physical) affair 8 years ago with a young guy half her age. This painful experience has never been fully discussed and my wife has never acknowledged the hurt caused at the time. She avoids emotional conversations at all costs and always has done.

The cracks were papered over for the next few years during which time I joined a sports club and met many new friends. It was nice to meet women friends who made me feel more confident after the devastating effects of the affair. Around 1 year ago I started a relationship with one woman I had known for 3 years. (I cringe with guilt while I write that sentence). I justified this action by the actions of my wife
a few years ago and the assumption that she wouldn't be concerned anyway as she shows no affection to me whatsoever these days.

I finally talked to my wife recently when she admitted she didn't love me and was open to discussing separation when I suggested it, which I feel is inevitable now after my behaviour (I am generally a very honest person).
I was very relieved after the conversation as it cleared the air, however I did not confess to an affair, nor was I asked.

My main objective now is to end the marriage with as little harm as possible to my (adult) kids who still live at home. I know it's going to be a stressful period for all concerned and I feel if I continue seeing my affair partner it may just tip things over the edge with all the deceit involved. My head is telling me to end my affair and avoid the risk of my kids finding out. I do love the OW but need time to sell our house which may take months and think she may lose patience in this time. I don't want to mess her around but I don't feel at all able to commit to her, infact when I try to think positively of the future it's usually having my freedom from a toxic relationship along with good relations with my adult kids which are the main thoughts. The question I ask myself is has my affair just been a way of coping with a bad marriage and should I make a break now and at least maintain some integrity until the split? Do I also confess to having had a relationship? I can't believe I have ended up in this situation as my personal life was always normal until I was 50. That's life I suppose