Dealing with a Mom as a Mom

I have always thought I had a good relationship with my Mom. But recently, I have seen a very manipulative side of her. Where it concerns my children- her grandchildren- she seems to want to be in control of the situation. She has tried to take over my role of caring for my sons where Doctors and services is concerned. I believe it is because she is fearful that they will not get what they need. Unfortunately, this reflects on me that I am not sufficient to provide the perfect care for my children. She has also offered financial advice. The result has been me feeling like she treated me like a 12 year old.
Well, I had a very difficult conversation with her recently where I was very respectful but was also able to let her know how I felt. I'm not saying it was a conversation without tears or yelling on my part- it was difficult. I think I kept saying over and over again, "Mom, I'm not 12, I'm 42. I have gotten really good at asking for help. I promise to ask if I need your help." There was also an issue of her feeling out of the loop with regards to these issues. I again assured her that I do let her know anything anyone official had already told me. I also let her know that I was not going to report to her every time a friend gave me an idea which might help.
I felt great and awful when I got off of the phone with her. Great because I was able to get rid of the feeling that I had to report anything that was happening with the boys to her. Awful because it really went against the people-pleaser in me. But I will get on with my life, and she will get on with hers. I am an amazing Mom to 2 kids who happen to have different needs. I almost wrote "Special Education kids", but they are really kids who have different issues than a lot of others although most of their needs are the same. I take great care of them and my husband and at 42, I can handle most of what is thrown at me with Jesus' help.