There is nothing wrong with stating a boundary and enforcing it.
Boundaries are to protect ourselves psychologically, emotionally and physically. Enforcing those boundaries has to be within our control as well. Your other friend suggested an exit plan. That is a great way to enforce a boundary. You can't stop someone from going somewhere but if you get uncomfortable with the situation, you CAN remove yourself. That is a great way to firmly hold your boundary without trying to control another person.
gentle hugs