Fuck it. Call them out on it. It’s a dick move. And it sucks that it’s happening to you while you grieve your father. I’ve emailed work on my days off too, and it was fine. I can’t imagine that being a problem for you. And you won’t be able to focus on your personal stuff with this work stuff looming in the back of your mind on your week off. I say address it.

I'm sorry for the loss of your father. I'll bet your scheming colleague had something to do with his murder. Investigate!

If your employer is human enough, he will keep your position until you return from bereavement leave.

You got friends at work? See about infiltrating and sabotaging. Let the boss overhear them gossiping about the snake stealing office supplies.

Be you! Be great at your job on your return. Don’t be ugly like them (you have lost a parent, they must feel for you). Karma will catch up with them.