Sex With The Ex

My ex-wife and I have been divorced for over 10 years but always stayed in good contact.
She got a new man, i got a new woman, we even went out with all 4 of us.
On sunday morning my routine is to go to the gym for a workout.
About a year ago (just after covid) i saw my ex wife in there. She needed some work on her body due to covid (she gained a few pounds) and we started to workout together.
It was nice to spend some time together, and seeing her in her yoga pants kinda turned me on.
She asked me about it ' are you hard watching me' and i said she looked hot in those pants.
She smiled and the next sunday she seemed to wear even tighter pants.
It became a weird tention between us, each time she was putting on a show for me, and i wanted to show how hard she made me.
Then came the day she was doing an exercise with spreading the legs, i saw her pussy lips through the fabric and a bit of a wet spot. i couldnt resist and for a second my hand was there.
She stopped the exercise, looked at me and i thought i blew the situation.
But she just whispered if i wanted to get out of here and go somewhere for a different exercise.

As teens, we always went to a secluded parking spot near the woods, it was about 5 minute drive of the gym. I drove directly to that place, her car followed mine. As i walked to her car, she got out, pulled her yoga pants down, bent over the car and said fuck me.
Since then every sunday i go for a workout, my ex and i meet in the gym and end up fucking.