Tips for overcoming anger and overthinking

A year ago, I (26F), found out I'd been getting cheated on for months by my boyfriend (28M), whom I believed was the love of my life. I was shattered for months. Our relationship was amazing, we had great communication, amazing chemistry, made a wonderful team, shared interests and hobbies, everything. This blindsided and destroyed me.

It took me a year to get over the deep pain and grief of knowing we would never have the life we (or I?) had dreamed of. To stop missing him. To accept what I couldn't change.

One thing I'm struggling to cope with, however, is the deep anger it stirred in me. Even though we aren't together anymore, I find myself feeling so deeply mad at what happened. At him. At what he did.

I find myself replaying our relationship over and over and over. Wondering what was real and what wasn't. Feeling insecure about all the ways in which I was different to the girl I was cheated on with. Wondering if i was just a fool all along.

This anger is consuming. This resentment towards him and myself has become a part of me. I overthink everything about us and our relationship. And even though we had several long talks where he explained everything, I still find myself feeling so angry, insecure and bitter. I still find myself analyzing everything that happened over and over.

Does anyone have any tips on how to overcome this? (ps. can't afford therapy, so that is unfortunately not an option)

Thanks.