When I heard about and starting trying to use boundaries last summer I told him all about them. It just created more tension for me and truth be told I wasn't ready to follow through so all I did was show him again that my boundaries meant nothing.
Now I tell him what I plan to do (if it will impact him in any way) but I don't ask permission or tie his behavior or response to what I do.
Ex. If he tells the girls he will be at the house to see them at a certain time and isn't here, I will make plans based on what the girls and I want to do and if we are not here later when he arrives, it is what it is.
Ex. I told him last night that I have told the woman who offered me a job in MA that I am considering it (I have a few interviews coming up here in my state too and am keeping options open). I told him that if I take the job in MA I will be moving there (he talked at me for a few weeks about how I should commute) and the girls will come with me. I did not ask. I am not keeping it a secret but I am not apologizing for my plans either.
Ex. I will not leave the girls alone with him. When I have plans to go out either my mother or a sitter will come over. I tell him when I am going out and who is watching the girls bc it is a courtesy. I let him decide if he likes that but regardless, it's what is happening bc he can't be trusted to not drink when alone with the girls.
These may not be boundaries exactly but I just gave the ex/ to explain what I meant about what I do...
Ultimately do what you are most comfortable with. You don't owe an explanation to anyone about what you do to keep yourself safe/comfortable etc...