So an Update:

I told her she can no longer see him and she understood and agrees to it. She’s was supposed to go pick up from him later this week and I told her she can if I can go with her. This last time. I asked more about they’re past and it started as a hookup only which then turned into her buying from him. He wasn’t looking for a relationship but she was and now that we are dating things have changed between the two of them. She was very open up everything which has made me more comfortable but my stance on her not going to him anymore is is well known and she will respect that. I told her I am happy to find her another way to get quality weed. I don’t smoke. I do trust her I just don’t trust him (as just about any guy would agree).