Need Advice Please

I am a 29-year old adoptee. I have been in contact with my bmom for 10 years now. My amom has always had a hard time with it so I don't talk about it with her. I have tried but she she has always been very emotional about it and very angry for some reason. She knows that my bmom and I are in contact. I am married with 2 children and my oldest is going to be 2 years old in October. I want my bmom to be at her birthday as well, so I decided to just invite everyone. I don't want to "tip-toe" around the issue anymore. Before I invited my bmom, I asked my amom if she would be okay with it and gave her some time to think about it. She was very negative about it and suggested I have 2 separate parties - which is what I don't want to do. Then finally she said "fine" but eluded to the fact that she wouldn't interact with her (which is fine with me). I invited my bmom and then 2 days later my amom sent me an email saying that she went and "talked to someone." She said it was a psychiatrist who told her that this isn't about me, this is about her (my amom) and that I need to take her feelings into consideration (which I thought I did by asking her and giving her some time to think about it). She said this person also said that I just can't "jump into things" and these things take time - so to sum it up, she needs more time. How much more time does she need? It's been TEN years!!! We've talked about it, I've offered to have them meet separately, I've offered to go to counseling with my amom and she always shuts down when it comes to that subject. I'm really torn at this point because now I have extended the invitation to my bmom and I really feel like a jerk taking it back. Anyone in a similar situation with a positive outcome?