What would you do if someone read and forwarded your emails?

So, I have been lending my father my laptop, because he needed to get a new one. Now I got it back and noticed, that not only did my father read some of my emails, but he actually forwarded a few to his own account. I’m 25, so he definitely had no right to do so!
At this stage I’d prefer not addressing this topic with him, but I also don’t want him having these emails. Any thoughts?