Hi
@europro
Welcome to the forum.
Letting people get close to us, or feeling able to get close to others who we find attractive, can be very stressful. With PTSD our stress cup is almost full at the best of times, so it doesn't take much extra stress to have it overflowing.
From the point of view of someone who has PTSD, your description suggests to me that she might be having some problems with her "inner critic"
http://pete-walker.com/shrinkingInnerCritic.htm
You write that she is in therapy. Has she read extensively about PTSD? if she has, she may already be aware of that link, and might not appreciate being sent it, but reading it will give you some understanding. For her, it is probably best if she makes her own discoveries and gains her own insights - rather than being handed them - just saying...
For me, personally, gaining a sense of "self agency" is a huge part of feeling good - receiving unsolicited "help" can really, really piss me off. By all means, let her know that she has not burned her bridges to you, but beyond that, if I was her, I'd be looking for some isolation time to calm down (update - I see you clarified that while I was typing :-) ).
One of the surprising research findings from the 1950s, was that people who managed to get discharged from psychiatric hospitals back then (a big achievement in itself, even today, people diagnosed with a psychosis stand a much better chance of making a full recovery and leading a normal life in places like Nigeria, than they do in Europe or North America! so much for the "medical model"), did much better if they lived alone in a bedsit, or stayed with a brother or sister.
Those who stayed with their parents, especially mothers! or a romantic partner (pretty much always a spouse in those days), had a far higher relapse and re-admission rate. This was narrowed down to an interpersonal dynamic that the researchers named "expressed emotion"
https://en.wikipedia.org/wiki/Expressed_emotion
What you can do is look after yourself. You come across as having a very good understanding of interpersonal boundaries, and of how not to become co-dependant.
Your view that you cannot be "just friends" is fair IMO. There have been partners in my past who I had feeling for that were so strong that it hurt like hell to meet them again after we had broken up. You know your own limits and it is wise to live within those limits.
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