Is it normal to despise your best friends?

I have 2 besties, D and C. Well, we've known eachother for 6 years, now in college, and have always been there for each other in the darkest of times.
A lot has happened in the past year, C dated some guy who, basically used her for sex, betrayed her, resulting in her going on a party binge, having a one night stand and getting pregnant. As besties, she asked D and I what she should do and we told her how we felt; all matters concluded, she got an abortion. Now, her decision isn't what bothers me, its how she continues doing the same dumb stuff that landed her in that position in the first place-its ridiculous! Then she's always asking me whether or not she should date some new guy every week, after I've directly told her to stop fooling around and focus on school!
Now I can normally handle dramas like that but to prove she's not some weak push over, she feels it necessary to make personal attacks at me. Not to sound egotistical, but, I honestly think its becuase she feels terrible about herself and wishes she focused more on work like I did. But, I can still remember the first time she delt such a low blow; I HEARD my trust snap.
I feel like I put all the work into the friendship and am constantly disrespected.