Hello & Welcome to Just Answers.
I can certainly understand your concerns, and appreciate the efforts you've made to help protect your daughter.
That being said, I don't trust the pedophile. It's him that I would talk to directly, and with your husband present if at all possible. You don't have to drag out the past, but you can tell him the boundaries that you expect him to keep: that he is not to be alone with her under any circumstance, and that he is not to touch her. Be very direct. He may stammer and protest, but if he was upstanding and in control of his behavior, he wouldn't have molested you.
Molesters look for opportunities, and when they don't present themselves, they create them. Pedophiles are sexually attracted to children - it isn't something that they grow out of, so you need to assume that he will be enticed by her. Many pedophiles are as much into the grooming of a victim as they are into the physical aspects of molestation. You don't want him working on her.
If you want to discuss it with your mother, you don't have to walk up and tell her you were molested. You can make the same point (since your stated goal is safety, not prosecution) by saying you had some very uncomfortable experiences with him that you don't want your daughter to go through, so you don't want them alone together.
Speaking your truth doesn't have to be a boxing match. Think about what you want to say and then say it. They may make a big fuss, but this is a very important issue. A grown man can outsmart an educated 13 year old girl. They do it all the time. Professionally, I think you've done a great job in preparing her, but she needs more help than her own resources.
You sound like a very good mom. Keep it up. Anna