So, I did the number 1 stupidest thing you can do when you get engaged (advice would be helpful)

A little background - I got engaged about a year and a half ago. We're planning on getting married in late 2017 or early 2018, just trying to get our lives a little more in order before we set an official date. So, I live with my FH's cousin, who I am very close with. Like, a week after he proposed, I was still so excited that I did the dumbest thing ever and asked his cousin (my very close friend) if she would be my maid of honor, knowing that the wedding was not happening for years. Fast forward to now. His cousin and I got in a HUGE fight (I won't go into detail, it was a very sensitive topic) a few weeks ago. Though we have made up for the most part, our relationship has really changed since the fight. She is still a dear friend and I want her in the wedding party, but I would rather my sister be my maid of honor. I know this sounds really terrible of me and I am not really sure what to do. It doesn't help that my sister (who I didn't ask) basically expects to be my MOH. I don't want to hurt anyone's feelings and it was so dumb of me to ask when I knew the wedding was so far off. Any one ever go through something similar? Any advice? Tldr: Asked friend to be my MOH a year and a half ago. We got into a giant fight and now I don't want her to be my MOH, but still in the wedding party, if she is interested. Wat do?