Have you read Dr Willard Harley's books 'Surviving An Affair', 'Love Busters', and 'His Needs Her Needs' yet? If you haven't, I highly recommend that you do so ASAP. Also read all the articles on this website.
It sounds like your WH(wayward husband) is a cake walker who enjoys having two women satisfying all his needs, AND he is not willing to end all contact with the OW and commit to rebuilding the marriage. At this point, going to Plan B is advisable for preserving what love you have left for him which is going to be essential if and when he does decide to end all contact with the OW and is willing to commit to rebuild the marriage. Marital recovery cannot start without those two conditions first being met, and if and when he does express a desire to meet them. In the Harley book 'Surviving An Affair' there is a copy of the Plan B letter Jon gave to his WW Sue which you can adapt to your situation.
You've seen firsthand that it is not enough to accept the word of your WH that he wants to end all contact with the OW and commit to rebuild the marriage, because he is like most WS that want to have both spouse and OP and not give up one or the other. The old saying 'actions speak louder than words' is so true when it comes to dealing with a cake walking WS. So what can you do? Stand firm and do not accept anything less than actions with respect of ending all contact with the OW forever, and to commit to a marital recovery plan that includes counseling with a pro-marriage oriented professional (i.e. Steve Harley, Jennifer Harley Chalmers, or Penny Tupi (our in house MB resident coach who goes by the username of Cerri) AND strict following of the principles embodied in
The Four Rules For A Succesful Marriage . These two conditions should be an absolute must for him to follow BEFORE you allow him to come back home, otherwise you run the risk of repeating history with another false recovery.