I am 23 and my life is really messed up due to porn & masturbation

I am a 23 year old and its been 7-8 years from the time I first masturbated and from that I want to stop it and I kept trying and I kept failing. Started with regular porn and stuff and then it was something or the other and right now I am in a relationship and I am so messed up that I have been sharing my girlfriends bikini pictures online over discord for guys to comment and I am jerking off myself reading that and I am doing this behind her back, I have all this fucked up fantasies and I am so so tired of myself, I really want to get out of this, Save myself from this and built a better future for myself and my family. I am a single parent child and I really am struggling since the beginning, I know nobody cares. Please help me.