Hi there,
I have to tell you that a very annoying stuff on Android is to manage your contacts and especially your groups of contacts. I think it is a big missing feature of Android.
But fortunately, there are some developpers out there that fill the gap

Indeed, I would like to introduce you the application called "
Group Manager" (by Tur Han =>
https://play.google.com/store/apps/details?id=com.mobappli.groupmanager) which is an android application that gives you the ability
to create or to update any google groups for any of your google accounts. Furthermore, "Group Manager" also allows you
to send a group mail for a given group and this is so usefull !!! And of course,
all your groups are automacally synced with your google account.
★ Features ★
▷ User friendly application
▷ Unlimited group creation/update
▷ Easy contacts picking
▷ Fast saving
▷ Sync with your google account
▷ pro version : group mail sending
▷ pro version : enhanced search bar
▷ pro version : select/deselect all your contacts with 1 touch
▷ pro version : filter management (various filter to dynamically display what you need)
Go and try it, you really won't be disappointed

link to the market :
https://play.google.com/store/apps/details?id=com.mobappli.groupmanager