I can assure you that you aren't the first person who has discovered that making the transition from high school to college can be tough--who breezed through high school and now has to study in college.
I am wondering if a large part of your situation right now might be caused by stress. As you say, you are having family problems, plus now you are having to adjust to a new situation. Is there an academic study center at your school? Or perhaps some tutors? I wonder if you are now sort of in a vivious circle--i.e., you don't do well, so you sort of panic, and then your panic leads you to not do well. If someone can get you to start doing better, then you can break out of that.
If there is no official center, then maybe you can ask around about a tutor--or even a study group. I even found getting another math textbook that covered the same material, but in a slightly different way to be helpful to me.
I hope something I said will be helpful--and you'll be pulling good grades before too long.