I made the biggest mistake i have ever made in my entire life?

Ok. Wow. So She's given you time to change. Thing about what you've done. Use that time wisely. You need to explain to her that you were experimenting and that you were just to embaressed. And how in time. You'd rather tell her then wait till she finds out from another person. I doubt it would be akward. It would only be akward if you didn't use your time to think about stuff. Towards the end of the holidays try getting her to agree to coffee, sit her down and explaing properly and calmly what you've just asked us. You shoiuld never give up. It sounds like you two have a very special bond and you need to understand how much of a friend she really means to you, if she means a lot then do as much as possible to get her back. You just need to get all your thoughts clear and think whats the best possible soloution. Hope i helped