Hi, I haven't been through your situation, but as a teacher I have seen children going through it.
Here is a list of some books you might find useful to read with your children over time
https://www.littleparachutes.com/category/issues/divorce-separation/
I haven't read any of these books, but it's worth looking them up.
It will be a big change for you all, as important it is to support them please don't forget to support yourself, as most importantly they need a strong mum too!
Also if they go to school/preschool, talk to their teachers about it, they often have support in school for the children and to keep an extra eye on them at this time.
Remember children are very adaptable, the change will be hard at first but they will hopefully soon get used to it!
My mum is a social worker, and often uses something called a social story to help children in separation situations, including their personal photos. So it might be worth making your own story and having photos of dads new house, and your house to explain they can go over dads to spend time with him, just focuses on what fun will come from the change, if you believe dad will still see them regularly.
Sorry I can't be any more help!
Good luck, and remember to look after yourself too! Hope your ok xxxxxx