Regret?

Yesterday I had done what I wanted to do for long time. I longed for it for so long. But somehow, I feel regret now. Maybe because it wasn't what I have imagined ot would be, or maybe because I thought so much of it. I dunno. Feels weird. As if I did something that I wasn't suppose to do. How to live my life further like this? This is so sickening. I want it, then when I do it, I regret it. So frustrating. Wish I could change myself for the better, for the one who doesn't care as much as I do now... Feels like crying...