I have found proof accidentally the person im seeing is lying about things what should i do?

i logged onto the comp first of all to check my facebook and hers popped up on a convo with her ex. they told each other they love each other and called each other baby.. she dogged me and he was trying to get her to leave me.i have also found proof of several other lies.. as well as not telling me the truth about medication she is on and y... she watches me on the comp like a hawk but she keeps what she does secretive... and if i bring any of this up to her she gets an attitude and starts blaming me for all kinds of things.she refers to the child support she gets as "her payday"and has had an attitude ever since she started hanging out with an old female friend again, but yet again if i mention it suddenly im the one with an attitude..her daughters came up and started hitting me in the back of the head and i told her if she didnt stop i would punish her and send her to bed... and suddenly i was the bad guy and she responded with oh she was just playing and said i had an attitude. this has been going on for weeks now as well as her constantly asking do you love me do you love me..and demanding kisses and getting mad when i dont snap right to giving her a kiss.i cant even go outside and sit without her coming out and askin where im at or what im doing or sending one of her kids out to find out.. then swearing she didnt.i could go on and on but ill stop with this... its gotten so where i dont even want to be near her all she does is argue and complain especially when she doesnt get her way... so i been stayin up late at night and going to bed after shes gone to sleep just so i dont have to hear her mouth.