I would say:

Dear Anxiety:

I understand, but that doesn't mean I like you. I understand where you came from. I understand my part in continuing you. I'm no longer inviting you in for tea though so I wouldn't mind if you would just stay away.

I have other ways now to keep me safe.

How about transforming? I can use all that energy for something else. Maybe for excitement and enjoyment of life.

Me

Dear PTSD:

We've been together for awhile. I know that initially you just wanted to help keep me safe. Some of you is made up of my survival tools but eventually you got out of hand. So it is time to re-evaluate our relationship.

I'm told now that you don't entirely live with me anymore, only pieces do. So you are already unraveling and losing your hold on me.

Good bye. I learned a lot and now I have other ways to learn and live.

Me