The first thing I'd do is reframe what's going on. You don't have a child who hates school -- you have a child who is still learning to separate efficiently from mom in the morning. Describing her (even in your head) as a child who hates school can become a self fufilling prophecy. Similarly, don't think what did I do wrong -- you didn't. You built a strong relationship with her so that she feels happy, and safe, and challenged, and complete with you, and it's a little scary to leave something that wonderful -- soon she'll feel all those things at school too and will go back and forth happily between the two.
Here's a few things that can work:
1) Quick, brief, ritualized drop offs, a kiss on her palm where she can wrap it up in her hand and keep it safe all day, or a kiss on her nose so she leaves you laughting, or something along those lines, the same every day whether she's crying or annoyed that you're slowing her down in her rush to get to her friends. Also, practice the drop off in advance. I've advised parents to come to school with Daddy on the weekend and show him how you do it. First practice with Daddy being the teacher, and show him the trick, then Daddy can be her (and be a little silly in imitating her) and show how he can be a big girl going off to school, then you might try and be the teacher and be a little silly (not imitating, but standing on your tiptoes if she's taller than you, or if Daddy's being her having him talk him talk in a squeaky voice or whatever). And she can be mom or the teacher too.
2) Playdates with kids at school, or staying on the playground after school to play with you there -- partially so you know enough about her social life that you can talk about kids by name, partially so she can make connections at times when she's secure to carry her over to other times, and partially so you can see that she's enjoying herself which will help you feel better and she'll pick up that vibe from you.
3) Planning for the high points in the day. When she comes home full of stories about what she did, make a plan "Really? They have that many blocks in the block corner? Wow, that house you made today sounded really cool, what are you going to build tomorrow". Then throughout the evening talk about her plans "Do you think you're going to try the monkey bars first, or the slide tomorrow?" "Will your castle have a moat, what will you make that with . . . " So that she's holding the image of the fun things in her mind.
4) Have someone else take her. If you've got the option of dad taking her in for a few mornings, or of carpooling with a friend (they do drop off, you pick up), it can make a world of difference to step down gradually from beloved mommy to school.
Know that this time is brief. You've got a kid who feels things strongly, and expresses her feelings to others -- that passion will be one of her greatest gifts down the road. One day she'll be loving school and telling you all about it in great detail.
Good luck