Visitation suggestions needed?

My 10 y.o. granddaughter, who I have raised since birth, considers my boyfriend of 15 years, her Papa. He left us 6 months ago. He saw us sporadically for the first two months, then quit entirely with no contact at all. I found out he was cheating on me for about 8 months prior, and eventually decided the other woman was the one for him. So the granddaughter meanwhile called him, texted him, and got no response. Around Christmas they started making phone contact. Meanwhile I've had NO contact with him as he TOTALLY refuses to communicate with me. I have spoken with the new girlfriend though, and she is scary, as in she says she has had a very hard life, and it shows in her communication. She's lived on the streets. She's made references to "taking down anyone who p*sses her off, that she'd just as soon kill them", and about her soon to be ex-husband being a crack addict, and more. Well, now, after 4 months of very little communication, he's made his first request to see her. My issue is this. I can get past the hurt he caused me/us by the way this all came down. He was downright cruel about what he did, but that's another story. I am a more compionate person though than spiteful, and realize this is her Papa, and he does have feelings for her, albeit questionable when he chose to ignore her attempts at contact. I'm sorry if this is long winded but you need to know some of the details. Well now he wants to see her, take her out, but insists it be with the other woman tagging along. I contend that she doesn't need to be in the picture at this point, that he needs to reconnect with his "daughter" first without her having to share him. They refuse and get irate calling me a controlling b*tch. It's been mentioned that they think I'm controlling it this way to get closer to him again. It's not true, I expressly told them that I would bow out from the meetings too so they can be alone, but that's not good enough - the girlfriend seems very insecure. No one speaks to him without being on speakerphone and she makes all the return phone calls or texts. Okay, just a little more. He comes from the streets too. I did not. I sort of raised him in many ways, but it seems he's gravitated right back to "his people", low life street people, alcoholics, and druggies. I suspect he's doing drugs and she probably is too, but I have no proof. He's not paying his bills, his personality has COMPLETELY changed, and so you know, he's a recovering alcoholic and drug user. Whew, this sounds like a no brainer, I know that, but I really empathize with a parent missing their child even if this isn't his biological child. Remember, he has absolutley no legal rights to her, just maybe moral ones, and probably not even those. Can anyone suggest how I can safely allow her to see her Papa? The courts can't help me by mandating supervised visitations, so I am confused as to going about making this happen for him, even though he seems to be fighting it by insisting it be his/her way. It might be coming all from her, not him, I don't know anymore. Okay, let 'er rip. Tell me anything you want. I am open to any and all comments and suggestions. Thanks.