I know this seems mean. But the issue isn't caused by your wife. It's caused by how you're interpreting her actions. Taking a step back. And unhooking your self esteem from her actions could really help. You genuinely are the same man you always were. Still a stud, when you're not anxious about things.

And a tonne of women would be happy to have sex with someone so open minded and fun in bed. It's her loss if she can't commit to you. And, if sex was such an issue for her. She would never have stayed in the marriage for 20 years unless your sexual compatibility was high.
I'd give yourself a little bit of a break here. Ending a marriage takes a lot of time and energy. So it's going to be hard to rush into a new relationship. Let yourself go through the emotions that come up, whatever they are. If you're able to talk to a therapist, counsellor or trusted friend. That can help to process what's going on for you too. Once you're feeling more stable, I think your sex drive will 100% follow.