I relate a lot to your dilemma Kashi.
My parents DID think I was faking being depressed (for 20 years...who on earth would fake that and deliberately miss out on having an enjoyable life just to get attention anyway?) I can totally understand why you would be scared of them thinking it's all an act if you recover.
I don't really have much else to offer here, but your post helped me to remember just how much I really was going through, and how much I struggled on my own until I managed to find good support, and that none of it was something I made up, despite having the same kind of doubts about whether I really even had CPTSD or not.
It's such a difficult thing.
I agree with the folk here who are saying that maybe your mother felt her purpose in full swing when you need her support, but no longer feels the need to be kind when you aren't suffering. In a way it is her own guilt and trying to make herself feel better for what she knows affected you. I don't mean to sound so cynical.