You haven't replied to any of the suggestions,so I don't know how you feel.

I've never had an affair with a married person. But while living with someone I wish I wasn't living with,I stepped out.

But it began with a Psychiatrist that was sexually taking advantage of his position and abused me for almost a decade. Also got me strung out on drugs( opioids)

So it became easy to screw around. I was over sexed party due to the opioids.
For 17 years.
So if you want to have one person and get married you could ask this woman you're seeing to divorce her husband and marry you.

Now that I'm a lot older,I don't think I'd have sex with someone I wouldn't consider marrying.

I know. An extreme position.

Good luck. Stay on track with work on your self esteem.