F.H.
You are not very clear on what exactly is happening. Are you having a prob with the hubs friend or are both of you and you want to end the friendship? If its just you then tell hubby he can hang out with his friend on his time and you don't have to be involved. if its both of you and you are concerned about the circle of friends, just let them know you are moving on from the best friend but still want to be involved with the rest of them and plan activities around the friend you are no longer going to see. good luck,