I'm so confused and dont know what I am feeling....?

Ok so my birthday is coming up really soon. U could say there's a tradition in my family, that when we turn thirteen we cam get a computer. I asked my parents for a computer and they said yes. The computer has already come, and my dad is setting it up. I was so excited to get a computer, so I could play sims, and be in privacy. I wasn't forced to ask or get the computer. Now I'm rethinking it. I have no clue how i feel. I used to feel excited, and just really happy. Now I'm crying and don't know what to do. I have such a good relationship with my family. There are 6 people in my family.....but my brothers stay in their room all day, and my sister comes out, but thats because she's 19. My mom said "oh great, now r we not going to see you all day now too?" I just feel like I'm not going to see my family, and waste my summer and birthday playing on the computer:'( I don't have enough will power, to stop playing on it, at least that's what I think. I'm crying and feeling so depressed, because I don't want it anymore if I'm gonna loose my family:( please help me. Just some advice on what to do would be great. Thnk u