Some men do this. I heard a woman speak on the radio whose husband just walked out one day and refused to speak to her again. She never found out why and she said there were no signs anything was wrong in the marriage.
Ignore posters speculating as to why he left. You don’t know why and neither do they. Hard as it is, you will be wasting precious energy agonizing over why he did this.
You need to be practical. As others said, apply through CMS. They are slow, so get on with this. Look into all the benefits you are entitled to and apply for these. Write down any details ypu know of his assets/ pensions etc. If you want to divorce ( if he has no assets and neither do you, you may decide this is not your priority. I know a woman whose H only served divorce papers several decades after they split).
You may be able to access free counselling through a charity, though chat gpt is surprisingly good for crisis support, I have found.
So sorry this shit of a man has done this to you and your daughters. Your priority is securing your financial and material future, supporting your girls through their dad leaving, and getting through it mentally yourself. Women before you have survived this, and so will you. Reframe yourself not as an ‘abandoned woman’ but as a woman who survives. You are in that long line of honourable history.