If someone is constantly causing trouble for me, how can I clear up the situation without both of us getting angry?

Lama Ole’s answer:

It’s best to say what one thinks in an honest and friendly way.

Just tell the person, without any anger, that you don’t like certain things, that they are unpleasant to you, and that you would like this behavior to stop. If the other person does not react even to repeated requests, then make some distance. Clarify the conditions under which you could live together, then, move out or throw him or her out if necessary.