Hi Mum!
I am in a very similiar situation with my AH. I have done all the research/leg work on how best to separate and protect each of us legally. I'm not out for "blood" so to speak - I don't want money from him, I don't want to take the kids away... I just want our marriage to go away.
My AH's response? Very similiar to yours. Doesn't want to talk about it. Doesn't want to hire an attorney. He tried to placate me by saying things like, "I'll give you whatever you want. Just write up the papers and I'll agree to whatever." So, he said that and I said, "Okay. I'll have the lawyers get the paperwork drafted." and then he FREAKED out! Why? Because I suspect he was hoping his "I'm a good guy and will give you everything" routine would get me to back down... that maybe I'd look at him and think, "Oh here's this great guy who's willing to give me the sun, moon, and the shirt off his back! I should stay married to him." But that's not what I did. I kept moving forward towards what I wanted and that made him mad. He's now snooping through all my stuff (email, cellphone, etc) - because he thinks there's funny business going on. I work as a municipal engineer so I have a lot of board meetings at night during the week... he told his mother that I'm not really going to board meetings - I have a boyfriend that I'm dating... that's why I want a divorce!!! Oh, I wish... because then I'd at least have some love and affection in my life!!! I don't engage in his attempts to manipulate me. It's not easy - but it's so necessary for my own sanity.
My advice - don't get sucked into the game. Focus on you. Focus on what you want for your life... and take the steps you to get there.