It's only as bad as you want it to be.
Six months ago I got fired. It was a sales position with the opportunity to run part of the business as the owner expanded. Long story short, the owner constantly flip-flopped with his employees, and three weeks after being given a "hit this sales goal in three months" ultimatum he gave me a choice of changing positions or being let go. It was scary letting him give me the boot instead of taking the secure position (which was a more solid paycheck, actually). I had already put myself in a little credit card debt and now I had no job to pay the bills. I was living with my now ex-fiance, but if I did not find a job I would have to leave her and move in with my parents. Talk about potential disaster.
I did everything I thought of to find a job. I used five job search engines every day and I had three professional placement agencies working with me. Even when I got down, I looked for something positive to keep me going forward. After only six weeks I landed a gig with a start-up investment business as the sole full-time employee - my job is to get two of their businesses off the ground so we can sell them. It's my dream come true!
I learned from the experience that I needed to do something I REALLY wanted to do for people I wanted to work for. Otherwise I'd spin my wheels going from job to job. At no point did I give up trying to find something I really wanted to do.
You can either take your firing as bad news or a blessing. You can cry your eyes out or you can take it to heart that the real world is not very forgiving, and sometimes things will not work out in your favor. You're 17, go find another job that you're interested in and give it your best shot, that's the only way you'll get anywhere in life. Heck, spin it to your parents that the company did not think you were a great fit, and you now understand a little better what you need to do to be successful. It's not the end of the world!
Go! Now! Find something new and be excited by it.