Masturbation on personal property=sexual assault?

Here's some background info: I dorm in new york city and recently lent a portable harddrive which i use for film and video work and currently have projects for clients stored on to a friend. In an act of revenge for a previous altercation he retrned it with seamen smeared all over it.....

It clearly could not have been an accident being that it was smeared on every side including the top bottom sides and power cord. I need a solution to not being able to work on projects for my clients because the harddrive they're stored in is covered in ejaculate...
What wold this incident fall under? Sexual assault? Sexual harassment? Destruction of property? Something else? Also.. How much would you estimate I would stand to gain in compensation? Thanks in advanced for any help. - Tom