.. emailed me her uncle has passed away
.. emailed me her uncle has passed on
.. emailed me her uncle died
What you wrote is fine. ("Angel"? If you have some prior knowledge that religious referneces are a good thing to use.)
Generally, in Western culture, for most people, feel free to say what you think.
Sorry to hear of your loss.
You have already stated this well, so no need for another way to say it.
Totally understand that you need to change the schedule during this difficult time.
Take all the time you need.
Please extend my sympathies to your whole family. (As if you know them, or would like to know them)
Usually advice includes things that are usually wrong for someone.
Take it slowly.
Take time to grieve.
Another thing, you could do, if you wanted to add more, is to ask, rather than advise. How's it affecting you? Were you close? ...