Wow, what a complicated friendship!

To answer your question about her dad dying - yes, she could still be depressed. My dad passed away 4 years ago, and there are some triggers that make it feel like yesterday. One co-worker in particular that I had a falling out with during the period of my father's death is still a big emotional trigger.

It might be that you remind her of the bad times As awful as that is, sometimes the people that are there in our worst times end up representing those worst times. She very well might be jealous of you, and your email may have been very hurtful.

I've sent emails like that too, and then regretted it later.

While it is possible that you might patch things up and be closer than ever, it is probably best to just give it some time and distance, and pursue other friendships in the meanwhile. Hang in there!