I feel a certain guilt for NOT going when I know she wants me to go.

(((( HUGS ))))

You are not responsible for her feelings.

You need to take good care of yourself.

I'm sure it's hard for her to fully understand.

How can we expect others to understand PTSD when we struggle too?

But if she's your good friend, she'll forgive you for not going.

Again, it's your call.