Can I still heal while being in a relationship with a toxic person, or living in a toxic family situation?

If you at least have access to a safe room that is your own, and have the ability to have boundaries about who enters (a lock is a good idea!) then you can begin the process. But, in order to fully heal you WILL need to eventually be in a safe living situation and be able to let go of, or hold very strong boundaries with, the toxic people in your life. Here is an article entirely about this subject: Sometimes we have to break up with our family.