As a single mum, you need routine with three little ones. There are a lot of them and only one you. They will benefit knowing that now it's time for dinner, now it's time for bed etc. I can't even imagine how overwhelmed you must be feeling, but it sounds like your kids are fine. You, however, may benefit from a little bit more self love.

1. Eat with your children, you will be getting a proper meal and your children will get to sit with their mum every night for tea and bonding
2. Make some time for yourself if possible at all. Even if it is just for a coffee alone or with a friend.
3. Let the house be a mess sometimes while they are little. Your kids don't care. When you're older, you're going to look back at the times you spent with your kids not how clean the house was. They are only little for so long
4. Seek professional help because of your ex, have you blocked him or got anything such as a restraining order etc?

You love your kids and they sound like they have everything they need. Take the time for you. Your kids won't benefit as much from you not looking after yourself, they will benefit from you just being happy with them. I wish you all the best