Of course you have value. I'm very sorry T didn't treat you like you do and her words and behavior left you with such wounds.
I suspect she knows both things....that you do have value and that she left wounds in what she did.
You are doing well in your grieving process, I think, if the moments are becoming more widely spaced in which you feel the hurt more deeply. It really does taper off......I think of my exT1 less now and the moments in which I feel hurt or angry are fewer and the emotion more muted, less intense.
I did write my 1st T a letter.....I tried not to sound too mad, too scolding, too abrupt/direct.....but the other day, something struck me and I thought, oh I wish I hadn't sounded so preachy, so scolding, so critical in some parts of it. I felt like I hadn't been fair to her....and I also had the feeling that I had forgiven her for the mistakes she made, because I do believe she was sorry for them and that the whole termination thing and the way it happened was hard for her too.....anyway, I'm glad I also told her in the letter that I was thankful for the good she had done for me and would try to remember the positive from our time, as I hoped she would too.
So, I think there can come a time, a feeling of forgiveness for you too....forgiveness for yourself, forgiveness for her, both. But the anger, the hurt, the grief are important to feel and work through.....and forgiveness can follow.....