I'm really sorry you feel this way. I strongly believe in an afterlife bc of certain experiences I had as a kid, which are strongly supported by all the stories about near death experiences, but that doesn't make the deed any easier to get to doing.
Feeling the relief however - that part I would argue is something you CAN feel relief from now, even if not emotionally then mentally. Just comparing how bad your state of life is now, to whatever you imagine happens after death (either an afterlife, which i believe is going back to the source aka pure love , so thats positive, OR no afterlife which means theres NOTHING, no pain, no thoughts, no emotions, you ceist to exist and don't know it, positive) both options are better than your life right now. So knowing you will one day not have to endure whatever you are enduring that makes you want to CBT is already a very small relief isn't it? Nothing lasts forever, whether through CBT or natural causes you WILL be dead eventually, which means this torment you are currently going through will be over. Now that makes me feel a little better.