contemplating break up

i met this lady who is currently my girlfriend around july 2014. we became good friends and later got intimate august. was never ready for a relationship but she kept mounting pressure on me. i really liked and RESPECTED her but i felt i didn't love her enough to commit in a relationship with her. she was very cool with with my friends and a couple of them even tried dating her but she really didn't accept but for one very close friend, i didn't know if she said YES or NO. she still claims she never accepted dating him. i finally agreed for us to start dating around January 2015 only to realize just after 4 days that she's been seeing my friend without telling me. i however got to know of that but she denied till she got to know i have empirical evidence. i however believed she never got intimate with him but she led him on (more on that later).
moving on, i had issues with her about her chatting with her past ex's. she still denied till she got to know i knew what i was talking about. so the relationship has been more of a begging scheme (on her part). i always considered her apology because i believed she was not doing anything intimate with them but the line of convo really hurt me.
She really hasn't helped me in my quest to LOVE her. I believe the love i have for her is not even up to a quarter of what she has for me. i just can't get the past issues off my mind. i don't want to pretend anymore. thinking of breaking up with her today. 
The more i think about what happened the more my love for her dwindles. what is basically left now is RESPECT for her and i think its not enough for a relationship.
 
NOTE: i'm 31 and this is my second relationship ever. broke up in 2009 and never dated because i felt i was never ready. and i enter into this relationship only to be faced with this issues.