Why do I feel sad, angry and stressed at the same time?

It all started when I wanted to buy a gaming laptop which cost $1.1k I m 16 sophomore in high school. I have a big feeling of getting it and I can afford it with my own money. At first I asked my mom if I can buy it. Then she yells at me for no reason and told me to save the money for college. I felt really angry when she yelled. At the same time my brother pisses me off by taking my stuff without permission and caught red handed. I haven t talked to my mom much anymore after since she yelled at me for that little reason. I felt stressed very big stress AND FINALS IS IN 3 DAYS. I felt sad and cried well adult actually cried where anybody can t see me crying. I felt that my mom doesn t talk to me anymore like she usually does when something is wrong. I just wanted to get this msi gaming laptop from this year thought out college and my mom said no just felt rage. I can t relax my feelings without someone talking to me. I just want to get the PC and be happy I have no other things to wish to get. Even my phone Nokia Lumia 1520 I paid my own before my mom did yelled at me a little. I just don t get why she is trying to control what I spend I know what I m spending things on plus there is 2 more years till college. What should I do now 3 days away from finals and my family is ignoring me except my dad which talks to me.

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