How to trust in God and move on from my past?

I’m a 28 year old woman and I notice I tend to dwell a lot in my past and my misfortunes. For example, I think a lot about my past relationships or people I’ve dated, or crappy situations I’ve been in, in general. For example, I broke up with an ex 4 years ago – he was someone I considered my first love and in many ways the relationship was traumatic. He was my only serious relationship and I haven’t been in a relationship since despite my best efforts. I found out he got married to someone recently which put me in a negative space for a day or so because I questioned my self worth etc. I’m happy he found someone but also felt a bit sad at the amount of trauma he put me through.

I tend to be really hard on myself and blame myself on things that are not my fault. I’ve been to therapy and my therapist recommends that I should just focus and appreciate the current things I have in my life and not look back or complain about the things I don’t have. My issue is that by doing that, I tend to invalidate or suppress how I really feel. I’ll brush of things that bother me and instead think “well at least I have a good well paying job, got the chance to backpack Spain etc.”

I’m in my late 20s now and I want to learn how to move on with my life and let things go for good. I feel like God keeps reminding me of the story of Lot’s wife and to not look back. I especially don’t want to waste anymore mental energy on people who probably aren’t thinking about me. Any advice?