Summary: Be an asshole or dump?

GF dries up. I find out about her past (she is 22 y/o and has a count of 30+, including getting nailed by two guys at the same time. They both were in relatioships). Discover she maintains contact with guys that used to pump-and-dump her.

Also find out she lied about going to sleep after we talked on the phone and went to some place at 0am. AWALT.

I am completly disgusted by the fact that I gave her my commitment for something she gives away for free for other men and don't want to take her seriously anymore.

However, the subject of getting another girl in bed always comes up and I think I can get her to do a threesome. Also, I really enjoy her company. So:

1- I could stay loyal to her and swallow my disgust. *Not my favorite option.

2- I could just not care about being loyal anymore. However, I have never cheated on anyone in my life and I feel like I am doing something very wrong whenever I think about installing tinder on my phone, for example. (I have developed oneitis for her again and care about her feelings)

3- Break up with her and endure another ~3 months of forced monk mode due to being broke. Not really monk mode though because I can't afford a gym membership.

Ps.: I can't get a job right now because I have a contract which will start in february next year.

So, my friends. Advice away.

Thanks in advance.

Edit: Removed details so people may read it.