3. Maintain Discipline:
As a boss, you need to give the discipline the highest priority than your personal feelings especially when you are a boss to your ex-peers. Pavan Mahajan, EVP & CRO, Aspire Human Capital Management, says that the discipline needs to overrule all the personal feelings in you, but at the same time you need to stand up for your team whenever needed.
Asif Upadhye said that, no matter how you felt about your peers in the past, but now as a boss, you need to start focusing on the collective strengths of your team rather than looking towards just the individual areas that needs an improvement. You also need to have the courage in you to draw a perfect line to your team when it comes to work and need to ask them to maintain a systematized schedule in which they can deliver their tasks within the given deadline. 
So, these are some of the main ways you can adopt if you are finding it difficult to become a new boss for your ex-peers. But make sure you earn the respect to your position from them as well as maintain your friendship just like the past if you can do it.