I NEED HELP GIRLS!

I need women advise so bad so if any girls have it that would be great. I have been going out with my girl friend for almost to years, I feel we have a great relationship. One week a go I went to china and I missed my girl friend so bad. When a returned home the first person I called was her.(before my parents) Her mom said she wasn’t home so I called her cell phone, nothing. So 2 hours later she called my and said her phone was off, I asked her where she was and she said at a friends house. I asked her what friend and she said her best friend and to other guys from work. I was so hurt that she didn’t even wont to see me. Her mom some how found out about this and phoned her and gave her shit on the phone and made her come home. She then came over to my house where she told me she was with just with another guy and that she hung out with him for the past three days. I got very upset, so we went to her house to talk with her mom. She then told me she just wants a friend who is a boy who isn’t her boyfriend. I of course blame her for cheating. She told me she doesn’t want anything more then a friendship with this guy and that she loves me. She told me I need to trust her or our relationship won’t work. I am ok I guess with her hanging out with him once in awhile but when she asked me if she can hang out with him tomorrow to that really hurts because I haven’t seen her in one week. Please help me with what I should do or think. I really think in my heart that she is telling the truth, but with her last boy friend she did the same thing but with a boy she said she liked, she said that’s because she didn’t like her last boyfriend and she didn’t want to be with him. She told me she wants to be with me and that she loves me.