Xpost - not sure where to get help to get more closure on open adoption

I'm cross posting this because I'm not sure what sections people would look at that could help with this topic...Long story short - My son is adopted from foster care. He was taken into care at 3, placed with me at 5, finalized at 7, and he's now 10.5. There was never an open adoption agreement, I told Bmom that I'd always keep her in the loop with phone calls or letters and that she could call me (After he's asleep) and I'd tell her how he was. Once things settled in and he said he wanted to see her I allowed him to. She called often, I'd ask if he'd want to talk to her and he'd say no, and so I'd talk to her and tell her how he was. Finally one day he said he wanted to talk to her. From there she called fairly often and I'd put him on - he never said he wanted to talk to her, but never said he didn't want to talk to her. The phone calls became excessive (as in every day, 4 times a day) etc. So I finally told her she could only call on weekends and explained why. It was VERY hard for me to tell her but his behavior was off the wall. I knew the boundary needed to be set... Things settled down. There are times she calls outside of what we agreed to, I just don't answer the phone... In the past I explained how he equates love to gifts and asked her to not buy him anything during visits and just focus on being with him - but she's still bought him things... We're going back to that area and we planned to see her (First time in 1.5 years) for a few hours. His behavior has been crazy and he's been doing things to not go on this trip. He's said some things about her (he doesn't know her like he knows me, he doesn't want to see her, he does want to see her, he only believes people love him if they buy him things - this is because of what he's been through and learned from her, etc.) It's tearing my family apart right now. I really think I need to stop contact. I will still write her letters, send her pictures, even talk to her on the phone when he's asleep... I'll even make videos of him and send them (not telling him that's what they're for.) He is in counseling, the counselor said we had way too much contact which is why I originally told her to only call on weekends. The counselor agrees the contact causes a lot of the issues we have and that we aren't able to move forward on things (like him learning that THINGS don't mean LOVE) because of the constant reminders to what he learned from her. Although I know this is what's best for my son right now - I have a really hard time telling her because I feel bad for her. I never agreed to anything more than phone calls and letters, even that's not legally binding, so I know I'm not lying to her and I know that I'm trying to do what's best for HIM but I also know that she doesn't fully understand what it's like for him or for us.... I wish there was a book or something I could give to her to help her understand... Can someone PLEASE help? We're going to visit in a couple days, I still planned on letting him see her for a little while but then thought I should tell her before or after the visit that the contact with him had to stop until he was a little older (visits would still be able to happen every 1-2 years as that's how often we go back to that area.) Do I tell her before or after the visit? Do I write to down or tell her on the phone? What do I say?