I definately can relate. I also became dependent upon my RABF for support. He is my best friend, he is supposed to be there for me right?
I can't tell you how much therapy has helped me in understanding how to get support from people who are PRESENT and HEALTHY in my life. They are there in yours. Therapy can help you find them, reach out to them if you have to.
Seeking support from an A is like leaning on a creaky old tree that is about to break so it just doesn't work. They cannot do it. You will fall to the floor every time.
The focus has to be on YOU and how to help yourself on your own with what you have in your life. The support for you IS there but it may take time to learn how to get it both internally and externally. It will get better.