Ok First time here, as the thread suggests i caused self harm to me, here is how i lived it.
(trigger, some gore expected with knives)

I had a wife and for 3 years we lived happy.
Once we lost the apartment we had to go and live to her parents, i worked 2 jobs in order to support us (we have kids from different marriages) and she cheated on me. I found out 2 weeks later, in which she said that she couldn't explain what or how it happened but she loves me.
Then i moved out and spent 1 week away from home only to return after sleepless nights talking to each other on the phone. She admited it but told huge lies to cover herself only for me to realise 1 week after. the same story keep on for 2-3 months. Every time she admited that she is lying and change the story, every day was a nightmare for me, i felt like i was made a fool of but i saw that she really suffered (she lost more weight than me and cried all day and night) which i couldn't make myself leave her.

then i managed to recover some data from "lost" facebook accounts and i had all the info i needed.
I asked her 1 more time if she was telling the truth or not before i check on the pc which she replied NO. Then i flipped, i saw that what ever happens she will never respect me enought to be honest. i felt like i was worthless which i decided to

Why did i do that? i was fully aware i was doing it but i never thought the consequences (traumatizing my wife and hurting other people in the process)
but at that time i wanted to hurt myself and am thinking maybe it was a way to make her respect me. or a way to make me feel something, or maybe a way to feel how little i deserve as a person to my wife, for never being honest.
I dont know what caused it. i traumatized the person i love and she is locked in quarantine and know am in ruins.