My friend is mad at me for stupid reasons?

my friend and i have been on the rocks lately, and she keeps blaming me. She is at a camp of some sort and wew were talking on the phone and i heard another girl in the room, i said "hey, i heard someone, hehe, can i talk to them?" but i was joking, but she put me on anyways, i didn't know what to say so i was like, um, hi," she said hi, then, agian joking, i say "i love you will you marry me, hhahahaha" she was like "bye" and really flat about it too. then i hear screaming from the phone. my friend was like "i knew you were gonna say that, i hate that about you (ouch) she asked me if you were a ! geez, what wrong with you!" me: "um, i'm you know i'm strait" her: well you didn't have to say that!" more talking we hang up, i thought we were all good, and forgiven, because she dropped the subject. Then on Facebook she said "i'm sooo mad at you for what you said to my friend" me:" um, sorry if it helps, but can your friend not take a joke?" ( her friend had told everybody that she had a friend, and anyways if i was a , which i'm not, what's wrong with being one?) her:"what type of a joke was that!?" i'm really tired of this type of thing from her, do you think i should forget this friendship or if you think i should try to mend it, how?