I cheated on my gf worst choice I ever made in my life

M 20) F 20 so this all started 4 days ago where I cheated but to understand everything we been together for a month now this girl has been so good to me gives me everything I ever wanted in a woman I have a bad thc addiction and it really alters my judgement I’ve been sober for 3 months aswell until my cousin asked me to smoke weed with him on his birthday and I said yes cause it was his birthday and that’s really where my down fall was and also my step dad has thc carts in the basement where I can just get them every night or anytime I want but anyways I’ve been really curious about this massage parlor place near my job and I would walk around it a lot cause I’m a security officer that has to go patrols every hour and after work I went it to see if the rumors were true and I could get a handjob I smoked lots of weed the night before so I wasn’t thinking straight and I went it I paid got what I wanted in there but as soon as it was done I have gotten the worst anxiety and panic attack cause i was realizing what I did and to her especially telling her all the times that I loved her that I would never cheat hurt her but I did in that moment it was the biggest mistake of my life or choice cause I just couldn’t believe what I have done I didn’t tell her for 2 days after that I couldn’t keep the guilt in cause I love her so much I need her so much I can’t live with out her so i knew I had to tell her or the longer I would wait the more it would hurt I told her everything she was disgusted upset and angry she left but she ended up giving me a 2nd chance we are working things out but idk what to do I mean Ik I can do better treat her so much better and never do some stupid shit like that again I need her I quit smoking weed nic and alcohol I can be better I just want what’s best for her but also I want her for the rest my life this girl is so important to me I love her so much I want to actually kill myself for ever making feel this way and I’m just so stupid and regret my actions Ik this can work out please give me some advice or tell me something I can do