Cheating... ()?

i told my gf that i cheated on her while she was gone for thnksgiving break. what i did is just kiss my friend i was high that time and it just happened.. i told her that before she told me that she cheated on me like a month ago. what she did is she slept w/ her friend. so i dnt really know what i feel. shes so mad at me bec. i cheated on her. i dnt know y is she making it a big deal. i just kissd my friend what she did is worst. she said that she still wanna be with me but idk if she really meant it. i love her so much and i dnt know what to do cuz were both hurt and stuff. i dnt wanna leave her. i need some advice... should i keep going out w/ her?