@HighwayToHell
Yes that all makes great sense.
My therapist suggested that when I feel angry because something triggers me into thinking my partner is betraying/cheating on me I not say anything to her about it but instead thrash about on my own, yell if I have to, and just let all the aggression, fear, anguish, etc. be expressed to the void.
What he says and what you say are essentially trying to achieve the same thing, which I appreciate.
I had a successful conversation with my partner tonight. I had a healthier day (more food and exercise), and I was practicing some techniques I learned today to maintain my emotions, so she was able to express all her feelings about things to me in a constructive way and I was able to respond calmly, kindly, and constructively in a way that left her feeling much better.
She said that because of my constant fear of abandonment and my angry outbursts, she feels like all the positive moments we have are forgotten and so my expressions of "I love you" feel empty. She needs me to show her with consistent action that I love her, and I cannot do that while in the grip of my triggers. I am hoping to maintain an upward trend from here on out... I really love her deeply and I want only the best for her and I need to eventually have the inner peace to consistently prove that. She has her own trauma that makes her susceptible to negative feelings, especially when I present with my own irrational negativity.
And she also told me that she does not think I am narcissistic, but when I am in the grip, some of my need for reassurance and my anger vaguely resembles what she experienced when she was dating an abusive narcissist, and that of course adds to her feelings of being unloved.
So, I am working very hard to get on the right track... Regular diet and exercise seem like a good start, and I just bought a good workbook on PTSD.
Also, she linked me this article, which was very helpful for us both (Thanks, Anthony). Well, I can't post the link but it is on here, titled "Are People With PTSD Self Absorbed?" It was great because I had just explained to my partner this whole thing in just about the exact same way Anthony does.
Thanks to both of you (and all) for the amazing responses. I feel so much more balanced than last night. It really is like night and day at this point...