There are two ways we can look at this from. The spiritual lens or the psychological lens. Spiritually, it's possible that this is now your curse for turning your back on God. If you feel this to be true, seek out a pastor for advice. Psychologically, there could be guilt inside for what you tried to do and now you have even more anxiety surrounding your speech which has only amplified the existing stuttering problem. I know you've said you've gone to therapy but have you found a therapist that you have been able to be open with about this ritual? As for myself no, I've never done anything like this but I hope this was still helpful.