you know hannah what works is not what you tell them, but how you guys actually work it out.
there is no one schedule. you have to find out what works for your family. what your children want and what you and your husband can actually do. make sure you guys have a flexible schedule in hand before you all talk to the kids. those are tough ages for kids so you will have to have more patience.
for us what worked was everyday. however dd was 18 months old.
but i think my dd is really well adjusted because she still sees her parents every alternate day. that works well for us, has worked well for us coz ex and i have made the transfers at daycare or school since we still dont get along. so while one drops off in the morning, the other picks them up in the afternoon. i kept her during the weekends as we did a lot outdoors, but her dad found it too much for longer than an overnight.
if you guys have been fighting and using raised voices around the kids - that's good news. that means the kids already know something is up and you saying something will definitely clear the air. if not it gets a little confusing.
i would make simple statements. if just a parent is moving out and you and the kids remain where you are, its a little easier. say daddy is going to live in another house ....
i am sorry mama for your loss. its not easy living through it. ((((HUGS))))
give them basics and let them ask you questions.
i would make sure both you and your husband are there to talk to the kids together. and ask them if they have any questions. mostly reassure them