If I was insecure I would think he was cheating but if you want and need to turn it around stop nagging him. Laura J. hit the nail on the head. If you have kids, get them out of the house and then make your husband a very tired and very happy man. Apologise to him for all the nagging and then tell him the specific things you respect about him. Feed his starving ego, physical appetite and his sexual appetite too. If it was possible for you to take some lessons in things like cooking (taking your culinary skills to the next level) or bellydancing (taking your skills in enticing him to another level), I know he wouldn't find his friends quite so appealing. Feed his ego and need for respect and you will get the love and attention he needs. Remember to be honest and sincere and it won't hurt to mention some of these things in front of his friends.
For instance a friend of mine and her husband were trying out a new restaurant, the menu contained items listed as Sexy 1, Sexy 2 and Sexy 3. When the waiter came to take their order, she said she didn't need sexy 1 because she had sexy 1 right there with her. Needless to say they had a "very lovely evening".
If you didn't have a shot gun wedding, you husband choose you and he really would prefer you over anything else but you have to do the work to continue to be a soft place for him to land and a conforting place for him to be. I really hope this helps. I know it works on my husband.