am i getting setup by my own girlfriend?

so ive been dating this girl for about a year now
things have been good but bad.....
the bad started when i got avicted from my apartment
and she let me move in everything was great!
2 incomes we could both afford it and we got along
great seemed like the picture perfect scenario
well about a month into it i caught her reading
a letter from a guy from prison ....
im not the kind of guy to flip out on her she said she
would stop and that hes just a freind
so i asked her about her past i wanted to know so she told me she was with 23 guys in 2 years!!!!!wow !!!
well about a month later another guy worte on her facebook saying he
loved her and missed her very much she said he was just a crazy guy with a crush .....
well about a week had went by and another guy ( a freind) randomly started throwing threats at me
for no reason and even put a meme picture online of me and the words said (im gay and i like big dick in my mouth
so i told the dude come talk...he never showed ....
well the next morning i went outside to start my truck and my tires were slashed ..
my girlfreind seemed unphased by it.... within a couple weeks i got my truck fixed
well then it happens again now take it i already called the police once on this guy so i had to do it again .
he admitted to the first time but not the second
about 3 months later i found out who did another guy i didnt even know and he didnt even know the guy who cut
my tires in the first place.......
so i sat her down and said look your (freinds obviously dont like me and told her i was leaving
she screamed and screamed and called them and told them never to talk to her ........
3 or 4 months went by and nothing until about a week ago the guy who cut my tires texted her phone
saying sorry she said screw off get a life then not even 10 mins later the other gy texts now these ppl
left us alone until a week ago .......this is the crazy part.....3 days ago she told me about her freind at
work cheating on her boyfreind because he got mad that guys were texting .....and last night i walked
in on her masturbating to a guy on an online dating site.....now i may not be ron jeremy but i know im not the worst in
bed why would she feel the need to have to do that when im home i mean cmon im the next room!! and what makes
it worse is when i asked her about it she left and didnt come home until this morning i have a good feeling shes cheating but i cant move
i dont have the kind of money for that i feel like im being targeted and since im a nice guy i feel taken advantage of i love her but
i feel like theres a past lifestyle she cant let go what do i do?