I would recommend dialectical behavioral therapy. It changed my life, especially when it came to emotional disregulation, rumination, and addiction.

There are plenty of meditation techniques that can help with swings in intense emotions. I use the app Balance which is currently free for a year. I use it just before I go to bed mostly but I'd I need to confront an intense swing of emotion it has come in handy. I am also doing everything you are doing and granted its taken me a long time. Also, dealing with your negative self-talk can change your perspective and ability to handle those emotions if your self-esteem is higher. It's not a simple fix but all of that really helps. I promise. Hope this is useful for you x