Being Promoted...

I began working at the restaurant about two and a half years ago. I spent about three or four months hosting which allowed me to really learn the ins and outs of this particular restaurant. This wasn't the first restaurant that I had worked in however, every restaurant is run differently. Once the owner felt that I had become comfortable with the atmosphere of his restaurant he promoted me up to a waitress. I love the hospitality industry because of the fast paced environment and being able to talk to, work with and meet new people everyday. After two years of working and attending school full-time I was at a place in my life where I needed to begin thinking about what I was going to do in another year when I would have my degree. Where was I going to go from here? What job was I going to look to pursue? About the time that I was doing a lot of thinking in this area of my life and career, my boss and the owner of the restaurant posted an Ad on the restaurants Facebook page about looking for a dining room manager. Needless to say I saw an opportunity and I went after it.
After about four months of talk with the owner about the position and what it would entail and how things within the business would change, the promotion was finally announced to the staff. There was many mixed emotions throughout the staff and business. This was something that had been discussed with the owner and I so I was partly expecting it. It took more getting use to then I thought it was going to take. I also had become close with many of my co-workers when I first moved up here because they were the people I spent most of my time with. Unfortunately I did loose friendships because of this promotion, but my career and my dream job is worth more to me then the friendship of someone who can not support me or be happy for me. Each day has become easier as I have been able to grow in the position and become more comfortable with my work and my authority.
The suggestion that I have with other people that may soon be in this same position or maybe in the position of being promoted over co-workers is that you need to believe in yourself. Believe that you got the promotion because of the work that you've done and the dedication that you have shown to your supervisor. You got the promotion over someone else because someone saw something in you and you just need to keep working hard and stay focused on your job and not worry about the drama that may come about.
My question is does anyone have any suggestions to make the transition easier and have any thoughts about keeping your head up and believing in yourself and the work that you do?