Regrets in Moving Forward

As heartbroken as I am to have lost my best friend, I am feeling much better about it now. Relieved, actually. She admitted to having used a small matter argument to do what she has been feeling was necessary for some time because she just doesn’t feel happy in our friendship anymore, and has no more desire to work through it even with our history. I’m sorry she feels this way, but I agreed that it was best we part ways.
I have been intentionally suppressing the happiness I feel about my pregnancy because of the guilt I feel about her losing her own child. I am constantly on eggshells, trying not to upset her delicate psyche. Am I acting too happy? Does she want to be happy today, or should I just let her be sad?
She never gave specific reasoning for wanting to end the friendship, only that she no longer felt happy or good around me. She also apologized for the way she handled it, but the horrible things she said to me are still burned into my brain because I KNOW she meant them. She picked the things she knew would hurt the worst, and used them shamelessly. I went back through the last few month’s text messages trying to find answers, and I do feel that I complained about trivial matters to her far too often. I’m ashamed of myself for having gone to her about so many of my stupid daily issues when she was struggling so hard to be happy as it is. I guess I’m just used to it, she is who I have gone to for every little thing for the past 10 years, and vice versa. In hindsight, I would not have burdened her with my annoyances or woes…but then I guess we would still be in a similar situation, since that’s what I feel friends are for. Any friend of mine knows that they can come to me with absolutely anything, no matter how small or trivial it may seem, and I will be there for them in any way I can. K is no longer in a position to reciprocate that part of friendship.
So much of her soul died with her son.