Trying to get my spouse to talk

I have read your articles listened to countless podcast-worked through the 7 day boot amp and tried to get my husband to participate. However it has been very minimal. I have tried to forgive and to tell him my feelings but he shuts down. I found out about the affai, we have been married for 35 years. I am not sure he would have stopped if I had not discovered the text. He is very defensive and not very open to discussion. At my wits end, I would leave if I didn’t have my children and grandchildren to explain this all to. How do I convince him to come clean-or attend a couples weekend?