Maaaaate! We all f*ck up from time to time! It's OK. Don't know where you're from but most colleges have a councillor please believe me it does help to talk it out with a kind stranger. So you're gonna fail this semester? THIS IS NOT THE END OF THE WORLD!! ! Hear me it really isn't. You have options, you might be able to take a break and then go part time so you can complete, or maybe a college degree is not for you at this time in your life. Believe it or not loads of peeps go through life without one.
I failed a semester during my degree, I tried again the following semester and ended up getting top of school in my results. When i asked the lecture about why he explained things differently he said he was using exactly the same note.... I just got it the 2nd time around.
I know you're feeling like s**t right now, but it will pass. If you do something permanent like topping yourself you can't change that... It's OK, you are NOT a worthless burden, I wouldn't be stuffed talking to you if I thought so.
I hope you can get through this *sends hugs* 
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I reckon they got it wrong, and it's the NTs who don't appreciate what life's all about