No life isn't "fair." And it's our problem when we think it's supposed to hand us a better plateful than it does others. It's a no win situation that one.

((((freewill))) This is common with DID patients: to have integration and then find that things fall apart for a while, going back to your old "habit" if you will, of using alters to handle the stress and grief and issues in your life. I don't think it will be permanent. You are stronger now than in the past. This is a setback, perhaps, but nothing un-fixable.
It's good to hear your Ts are keeping track of you and caring for you. PC members care too. Do stay safe. After you're done screaming, you'll figure some things out. I believe you will be able to do this.