First...I wouldn't dare give out legal advice here or anywhere. I WILL say this: you will want to make sure you have documentation of when you were diagnosed, the severity, the treatment you went through and when you were released and "cleared" by your therapist/psych doc. If you were "cleared" then it seems that you are not a current sufferer, correct? I don't mean to trivialize your experience. Please understand that.
Second, get an attorney. Someone who specializes in cases that include problems with spouses who claim mental illness against the other.
Third. Find someone to talk to STAT. I have been through ugly custody battles and it eats at your soul in ways that you never knew possible. It can bring forth reactions and stress that will age you in ugly ways and bring out the worst in you. You don't want or need that. If you need to find a therapist to help deal with this, find a way to do it. I can honestly say, years later that I wish I had.
Fourth. I am NOT saying that you do have a problem, but IF you do have an issue with anger or anything that might make her think that you could still have PTSD, go get it addressed RIGHT NOW. No judge wants to take away custody from a parent. Even IF you have problems that fall under that PTSD diagnosis or any OTHER diagnosis, as long as you are making good faith movements to a healthier you, then they are not going to remove parental rights. You may not get primary but you will get joint custody/visitation. Crack users who go through treatment get their children back. There's no reason to think that they would take your child away from you completely because of a disability.
This is a tactic to illicit an emotional response- usually provoked by a very strong emotional response from her. Stay level headed. find a way to maintain your stress levels and breathe!
And finally know this: your child will ALWAYS BE YOUR CHILD. This is not a race. This is not a competition. Your baby will be your baby 20, 30, 40 years from now.
Breathe.