I can't remove my Windows partition anymore with bootcamp!

I installed windows XP over a year ago on my mac using bootcamp, now I would like to remove it completly from my computer and get back some space.

So I opened bootcamp and the only option was "Install or remove windows 7 or later version" so i did that.

I waited a bit then a message poped up saying that the operation failed, so I try again and it keeps on loading loading, so I leave it overnight and when I check it again it hasnt moved its still where it was last night so i click on it and it was frozen and crashes, so I open it back but this time the "Install or remove windows 7 or later version" is gray so I cannot click on it anymore, and I still have the same amount a space that I did before even on disk utility I cannot see the windows partition anymore. . . even on system pregerences -> startup disk. the windows partition is gone. its like if its gone but where did the free space go? i had 50gb of space on it and I dont know where it is how to get it back?

what is the problem please help?