Listen up, you are NOT a failure. In elementary and middle school I was not a good student, I had family troubles at home, and I never expected to me where I am today. I go to Univ of Michigan and pulled all A's this year...I am telling you this to ENCOURAGE YOU. I took all the ******** in my life and tried to turn it into something so that I could succeed and one day take care of myself. I never expected to be where I am today or get the grades I am getting. Ask yourself these questions:

1. Do you study hard? If so, great but perhaps you are focusing on the wrong areas and in which case I'd recommend going to see your professors---if you take the care and intiative to go see them they might not fail you if they know you're trying. They are also great at clarifying concepts...and if you are borderline on failing, I hear a lot that if a professor knows you at least tried and came to see them, they will pass you. If you dont study perhaps that's why you aren't doing well...remember college is much harder than high school.
2. Do you procrastinate? Putting things till last minute is never good, get college work and studying done first.
3. Create a private and personal workspace. it sounds like you get a lot of grief at home...why not try going to the library to maintain a good focus.
4. Colleges offer FREE tutoring, really really take advantage of this. Its much easier going to tutors that are your age who can help you, moreso sometimes than professsors (especially if they are mean, difficult, or confusing).
5. Arrange study groups with people in your classes, use flashcards, anything like that can help you.

Good luck and remember you aren't stupid nor a failure. Everyone struggles with something in their lives. College isn't susposed to be easy Let me know how it works out!