How can I get a legal document which would prevent my husband from purchasing property in an irrevocable trust, where he is the only trustee?

I am in a marriage where I do not have any access to money or credit cards. We own a business, however, I am not on any of the corporate articles, etc. We are going through an infidelity issue, and I have asked for a separation, for myself and my son; while we receive therapy and healing. Living under the same roof is very toxic. He wants to be in control of where we live and is wanting to purchase a house, in an area I do not wish to live, (from a friend of his; who will carry the 10% down. If I don't agree to live there, he will purchase the home and stick it an a irrevocable trust, he has set up for our children, in which I have no control or access. He has himself listed as the only trustee. He bought another home in 2012, and created the trust at that time, because I was not on board with his decision. He told me yesterday that he would move forward and do the same thing now. I do not feel like we are in a good place, and making this purchase together is a manipulation tactic.