How to deal with housemate?

I swear something is not right with her... so there's this housemate of mine who constantly hits me (like today its in the head) and acts like she hasn't done anything wrong and sometimes verbally abuses me... Is this normal? and then she acts like it never happened... so it is kinda awkward for me? Im a guy btw dont want to retaliate cos that would be wrong... we dont really talk because i find her too obnoxious.... and laughs at every single thing(she has got the most annoying laugh).... these past few weeks everytime i go home i've stayed locked in my room just for the sake of avoiding her and only go out of my room when she's out somewhere.... i can't move out because i just moved in... and its not easy to find a house and plus its closer to my uni....