I don't know if you are familiar with EFT, but you could try tapping on the points and saying something like "even though I feel like I have failed, I deeply and completely love and accept myself" and say that for a few rounds, then progressing onto saying "I let go of all guilt relating to my part to play in this marriage breaking down." and just keep saying the sentence "I let go of all guilt completely", "I release all guilt...I let it go" and just keep saying that for a while. Then when you finish, stop and tune into your body and see if you feel anything loosening up.
It may take a consistent effort before anything starts to shift, but it might help? If you've never done it before, you could try looking on you tube, as there are many different videos that show how to do EFT.