Hi, I don't have any bike specific advice but I wanted to wish you luck. Don't have experience specifically being hurt biking and afraid to try again.. But yesterday I tried to deal with a phobia of my own and did a terrible job of it. Was actually thinking about it while I was reading posts here.
I can empathise with the PTSD.. Sometimes even unrelated things open up a mouth to hell of other things which are overwhelming beyond reason and beyond what started the downward spiral of worry or even flat out terror. All of my sympathies.
Wanted to let you know though, that somehow reading your post has made me more confident about overcoming my own phobia. Other people have done it, You can do it. And I'll be able to do it to. Sorry if this comes across as naively optimistic. Your post has helped me relax about my own fear... Thank you for that.