How Do I Let Go of My Old Identity?

I struggled with health anxiety for 7 years, and for the past 3 years my life has been transformed and I was able to overcome it.

However, I was left with an event that at that time (3 years ago) I really blamed myself for (even though nothing actually happened and my mind just offered my a thought of the worst that could’ve happened). So for the past 3 years I really lived with the guilt of something that I thought I did (my brain was telling me that I did) when in really I did not. I have worked on letting go of that guilt and moving into a new version of myself, however I find it a bit hard to fully let go of it. Or when I do, I get other anxious thoughts about my mom’s health and what will happen to her, if she will be ok and so on.

It just feels like it is part of my identity to continue worrying so I’m not sure if that is the reason why even when I let go of something that has been making me anxious, my brain just makes up another thought that puts me right back into fight or flight.

How do I let go and embrace my new self? How do I move forward and let go of that old identity?
Thank you!