What should i do about my parents?

ok...i dont really know how to ask this...heres some info bout this....im a 13 year old kid who gets yelled at by his parents...alot.....first thing is that my parents continually say that i should go to boarding and military school and threaten me with it about 3 times a week....my mother is usually who says it.....my mom yells...alot.......if she is already mad and i do even one thing different then she asked she will explode.....a few days ago she cussed at me for about 20 minutes because i forgot to do my laundry? (calls me a piece of ****, etc)...another day i broke a gl when my friends were over...she took me downstairs, slapped me, and half-kicked me in the stomach but hesitated.... i just wanna know if this is normal for parents.....it all started about 2 years ago....i used to be a very cheerful little boy, who felt emotions and feelings and enjoyed being with my parents, then when i turned 11 they changed, and the slightest mistake goes very harshly punished after awhile.....this is me after 2 years, i dont feel anything, my only happiness comes from my friends, i used to cut myself alot...(my friends stopped me for awhile but i...i just started again:(....ive shut off my mind to the point where insults and words dont bother me..only my mom can actually hurt me....she continually knocks me down, makes me feel like dirt, worthless and awful......but then whenever someone else is there she is a completely different person.....i just dont know how to deal with something like this....can someone just give me some advice....