SAHM going back to work tips, advice

I've been a stay at home mom for the last five years. I need to go back to work part time to help our family get over this slump we are in. We don't use any type of childcare just family helping out so I will mainly be working weekends and nights My children are both very young (almost 2 and 4.5) so I don't THINK I have to worry about any long term resentment for me all of a sudden not being with them 24/7 but I get incredibly emotional when I think about leaving them. And of course I will miss my husband since I will hardly ever see him, but he understands. I need advice! It's not very professional walking in to a new job crying...