I'm going away in a few weeks and my mother has done this to really annoy me?

I had a map of usa on my wall with all the states and it was a poster, I marked with a pen all the places and routes im travelling etc i practically lie in bed at night and dote on this map because its a trip im really looking forward too! I came home from work one day and my mom had ripped it down and shoved it in the corner of my room and it had rips in it and stuff which it was perfectly in tact before. I said she shouldn't have done it and i paid money for it off line (because its quite a big detailed one and i live in england) Im 21, im trying to make it look right aagain but it looks a mess and huge chunks of rips in it. she said i have no right to be pissed off and when i pay the mortgage i decide what goes on my wall even though i pay her housekeeping. Why is she being like this? do i have a right to be mad?