Practice setting boundaries.
Phase one: Understanding yourself first
1. How do I feel about this situation?
2. What are my values in this situation?
3. How would I like to be treated in this situation?
4. How would I treat others in this situation?
Phase two: Removing/releasing false expectations and fears
1. Write down any ways you fear the person might react or respond to you when you communicate your boundaries/needs/wants/desires to them
2. If you wish you can then spend some time crossing these out, burning the page or in any other way you see fit ritualistically releasing these fears and false expectations.
Phase three: Practice clearly communicating your boundaries
1. Write a letter to the person involved, you can choose whether or not you will send this letter.