Do I even need a separation agreement?

I have been out of the house for about a month. We have no tangible marital property. I have two children from a previous marriage whom I have custody of, and who are living with me. I have a good case for Alienation of Affection should I need to peruse it, but really don’t want to at this time. Can we just agree that we separated on the day I moved out, and wait our year for divorce. Or is there some other reason I should have a separation agreement?

You won’t really need a SA if you have no children together and no property. A SA will cut off inchoate property rights as well, but you do not necessarily need one at all. You can wait until your separation time has passed and then file for a divorce. You will not be able to ever file for equitable distribution or alimony once the divorce is finalized, but if those aren’t relevant to you then you are okay.