I'm with cadence here...but if it really feels not you-ish (if you know a bit of you is doing it out of spite, or you think you'll feel good about it for a day but regret it in a year), why not ask your L to suggest a middle-ground prompted by his text about finances?
You do need to be canny though because if you give him too much notice, there are plenty of stories here of spouse's emptying or freezing joint accounts. Talk to your L. Help her help you find a more T-ish way to do what you know you need to do for you and your little ones. x
Me: 53 H:38 T:20 M:14 BD ILYB etc 10/15, H diagnosed severe depression S 1/16 PA 4/16 H filed 1/17