How much more do i try to get her back!!!!?

well where do i start other than i made the biggest mistake of my life 1yr ago i had an affair with another woman for about a yr and my girlfriend found out about it after i broke it off and made a real committment to our relaltionship i took advantage of everything that is real and true in a relationship and i know that i am gonna lose the best thing that ever happen to me we have been together for 3.5 yrs since the betrayal and time she has found out about it i am trying to do everthing i can to prove and show her that it will never happen again i am in love with her so much and also her daughter this has been an emotional roller coaster for both of us but i dont know whether to keep trying to make this work i am in counseling right now have read different books on infedility and betrayal but she still tells me that she will never be able to stop wondering if i will do it again and this was done to her in her first marriage also so you can only imagine on how she feels again i want nothing more than for us to work this out but i need her to be with me on this but just not sure she is gonna be able to get through it and let me prove it so basically should i keep trying to show her i do love her and i am greatly sorry for this or just let it go i have not really given her time and space i have been hounding her with everything that i am willing to do just so i can keep her close and not ready for this to end