BW Good morning.....
Sooooooo, another difficult day for you. First off, just to say that you need to get your nerve back and centre yourself before you start to make any decisions.
Now, you say that you wanted DH back for the sake of the children. Well, think about this for a minute - three scenarios:
First, he comes back as he has said and things go back to the way they were before. So, in this instance, DCs have both parents back together - one parent (DH) doing exactly what they want to do. Other parent (you) a nervous wreck and downtrodden, frightened all the time in case DH decides in a few weeks/months that this is not what he wants. So, your DCs have one happy parent (DH) and one miserable, nervous, exhausted parent (you) who is running on empty and can't give them the love and hope that they need.
Second, he comes back under the strict proviso that you both go to Relate and both have counselling which MUST NOT stop after the first session and MUST carry on for what may take months.....
Third, you decide that you need to keep you (ie. your heart) and your DCs (their hearts) safe from the possibility of your DH doing this again and you decide not to have him back. Now, you will need to explain to your DC who are old enough to understand, that this is so not their fault, that Mum & Dad can't live together anymore, and that Dad will still be around and they can see him, he just won't be living with you all. Your children WILL NOT hate you - please stop believing that they will.
There are little bits of fun that you and the DCs can have which don't cost a lot of money - just a little bit of time. I used to do "dinosaur parties" for my DS when we were first on our own. Just get a pack of Bernard Matthews Dinosaurs, a pack of Smiley Faces and some baked beans or peas. Then, a tub of ice cream and pay a visit to the baking section in the supermarket - get some chocolate sprinkles, some jelly shapes or whatever takes your fancy and let the kids make their own mess ice cream toppings.
It's little things like that which do help. You keep that doctor's appointment this morning, and keep shouting out on here - we're all STILL behind you......