You don't have to like her, even if it's possibility. You can be jealous because you want her to spent more and more time with you and you are afraid that she won't spend time with you as she did. But try to think about her being happy with that woman and that she needs to have fun too. You may think that you have a crush, and maybe you have, but you'll know if it's love or not when that jealous feeling will be there for more than a few months. I think we all been in situation when we thought we might have crush on our friends but that moment faded away. When you'll discover that you like her, it's not the end of the world. You'll find someone else that you will like and who knows... maybe you'll end up with your best friend. I am just saying, it doesn't have to be crush. It can be need for attention from your best friend.