Any tips to regain self-confidence after being cheated?

My fiancé cheated on me for six months after a lomg term relationship between us
He always criticized my body and that I was skinny (my weigh is 52 and my height is 166).
I no longer trust my look or my body
I trusted him a lot and never doubted him
I want him to regret it

Any tips to regain self-confidence after being cheated?
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