What do i do about a girl who wants to cause trouble with me and the boy i like?

Well she use to be one of my bestfriends, and idk what happend.. so the one night me n the boy i like was talkn and he asked me if i liked anyone, and so i eased him into tellin me who he liked and he said me. i also told him i liked him too.. anyways, so later on that night he asked me if i could have a bf and i said i dont really want one right now, he understood and was willing to wait till i was ready... anyways, the next night he txted my friend and i didnt care cuz i knew he already liked me, but he asked her if she could have a boyfriend and she said yes, but he was just asking to ask ya know? so he changed the subject, and then this girl told me he said he liked her, and we all then she told him i was mad at him, and then that just set him off cuz he didnt know what was goin on, so i said show me the txt that said he liked you and she said "oh i erased all my conversations, sorry.." and then after about 30 some minutes she told the truth about how she was lieing...... What do i do about her????