I 38F am looking for some insight into a current fight with my partner (40M) of 16 years

I want to keep this somewhat short because I am emotionally and mentally taxed.

We had a fight about a week and a half ago and haven’t spoken since, I keep trying but he is just seeming cold and detached, doesn’t want to be around me and ‘has nothing to say to me’… we have kids and the stonewalling towards me is shifting the energy in the house.. I don’t know what to do, I have no idea how to breakthrough to him, or if I even can. Like at what point do you know a relationship is dead and repair is no longer an option? Is separation drastic or inevitable? Has anyone ever fixed this and if so, how? Thanks for reading 💛