I'm really big on R when it makes sense.
You have a very tough hill to climb for your wife gave away things to this piece of garbage OM before she gave the same to you.
This can be a tough forum and I want to warn you this is going to be a tough viewpoint. In some way I lived out some of your story and survived it. Had there been an SI decades ago, I'm not sure I would have gone the R route. I was a weakened, strongly affected victim of a really bad A, was hurting so bad that I couldn't be decisive at the the time.
In your case you're suddenly really liking the sex. I'm trying to be honest. The only thing different now than before is that she's all in on all the sex you want when she was sex starving you for a long time. She's sex bombing and love bombing you.
The reason I knew my fWW was involved with a POSOM was the sex stuff she took home. She was suddenly "really good at" certain things and it took real practice. All of a suddend it felt like I was with an experienced prostitute. He had schooled her on how to deliver sex. So she had become his little porn star and he gave her guidance on the nuances of what he wanted. I am not grateful to him for having done that.
In your case you indicated she herself indicated that he had given her "tasks" to do. So you started out with a somewhat sex resistant wife and somewhat experienced woman and ended up with an experienced porn star. She had accepted his urges and guidance on how to deliver sex and then suddenly you're into things with her you never did. That's because THEY did it. It will weigh very heavily on you that your WW got schooled on sex practices by that POSOM.
Your WW started out thinking about other men. Then she got approached by a much younger (I think 27 or something) guy trolling for sex and he found her. She was out there thinking about slutting and then went off and got into slutting, big time. All the way to bringing that garbage into your home. She not only brought the sex home, she brought him home and an STD home. Along the way she really got into her "real inner self" that involved really hot sex with a really hot guy she really wanted. Any other story is a big fucking lie, complete. In my case I got the ex USMC dude who hit on my fWW and she went for it. I inherited the aftermath.
I'm not here to encourage you or discourage you from continuing this relationship. This is your life and your decision. You should do what you really think is in your own best interest. I do, however, want you to carefully think about what I said and how you feel about that and see if you feel you can live with all this in the long term. It won't be easy.
In my case we went on to a successful marriage and successful family. It is still with me until this very day about her and the POSOM and how she gave herself so ardently, willingly for up to 18 months. Sex on demand for someone else is a rough road to recovery from and in most cases the recovery is never complete, especially when they explored new territory. It can recede in our minds and then return over and over, much much later.
Consider all what I said and I wish you the very best. Good Luck.