I'm using a throwaway because my friends like most here are heavily involved in reddit, and i just dont need more drama from this. TLDR at the bottom.

I fucked up, first of all. I knew this bitch had a knack for lying, being manipulative, and using everyone she could. But instead of the fine logic i read from lurking here? I ignored that voice in my head and pursued this waste of space anyways.

Some back story bros, I've known this girl for over 10 years. We have a similar sordid past involving drug abuse and personally ive been clean for 5 years. She's been clean for almost 2? She has a completely tarnished record, from being dumb and getting caught multiple times. Even to the point of using while being pregnant and having her baby in jail.

She was extremely pretty at one point, pretty enough to strip and make great money at it. Although now that she's put on 35 pounds and her rough life is catching up she's not as pretty. But I still find her attractive. Especially since i can tell shes clean (on probation, random drug tests). She started to show an interest in me, romantically.

I wont lie, im pretty chubby (6'2 250 and dropping) and also not very rich so, you can imagine ive been looked over by many women over the past decade+ (28 now). So I've pretty much always had a crush on her and she used that to her advantage. We started talking and getting close, and she wanted to introduce me to her "best friend" named..well, it might as well be Chad.

Chad is a loser but more attractive than me. He lives in a one bedroom shithole, and doesn't even have a car at 30. I live in a two bedroom house which isnt the Ritz but i am self sufficient. We hung out last night, got a little drunk, played some guitar and sang(we're all musicians). She sleeps out on the better and bigger futon in the living room with me and of course my pleb ass takes the shitty one.

I hear her giggle and wake up but i pretend to be asleep, hearing Chad's bedroom door close. It's before sunrise and i look around, shes gone. I hear more giggling and hushed whispers then eventually the occasional moan as they start fucking. She had the audacity to fuck this dude in the next room over. I started shaking, suppressing the urge to just jump up and leave. Oh btw, i had been helping her get to work on occasion for free, basically. I'm an idiot.

She comes out and immediately i tell her if you need a ride home get your shit together. Then i go sit in the car and wait. She comes along ten minutes later and we leave on our 30 min ride home. Like usual she lays her head on my shoulder, tries to hold my hand but im not having it. She knows something is up but i dont say anything.

My question is bros, should i just kill this long term friendship and cut all ties? Or act like it doesn't bother me and just keep it casual?

TL;DR

Crush on girl for 10 years, she shows romantic interest after fucking her life up with felonies, takes me to "BFF" Chad's house, fucks him when she thinks im asleep, what do?