OP, I am so sorry this is happening to you.
I was in a similar situation 4 years ago. My ex financially, emotionally and psychologically abused me, but I didn't see it until it was too late. This will be long, so apologies.
First: Men generally don't up-and-leave because they are unhappy. There is high probability that there is another woman. Get yourself tested for STDs as soon as you can.
Secondly: Secure your finances. Print out statements of all your bank accounts, make sure the date is on them. This way, if he tries to drain the accounts, you can prove how much he stole from you in court. Open your own bank account and have your salary deposited in there. If you have a joint credit card, get one in your name only. DO NOT DRAIN THE ACCOUNTS BECAUSE THIS WILL LOOK VERY BAD IN COURT.
Thirdly: You need legal counsel. I am from the US, and over there, I have often read that you should seek out counsel from as many lawyers as you can - the sharkiest ones you can find - meet with them for that initial free hour. Why? Because then your soon-to-be-wasband can't use them - it's a conflict of interest. Work out a payment plan, borrow from parents or friends back home if need be. But make sure your all of your legal bases are covered - especially if your children are minors. Insist on child support, even if you think it will be easier to let it slide. There might be financial obligations later you haven't even thought of. Although I am American, I live in Germany, and most divorces end with both parents having legal custody. This has ramifications on decisions regarding schooling and medical issues. My wasband insisted the children be insured through him (although it would be free through my insurance - but he thought he could control their treatment - he can't, because they are over 14 and can make their own medical decisions), but as it stands, every year we have to meet a 500€ deductible before insurance will start covering bills. Our younger child has ADHD (which my ex doesn't believe in), and the doctor-ordered therapy costs 900€ every 10 sessions. The latest bill just rolled in and guess who got stuck covering that deductible? I have to figure out if I can get that money back. But I digress.
Fourth: Find and make copies of all important documents: birth certificates, marriage certificates, deeds to property, proof of major assets like cars, at least three years of tax returns (which are often used to calculate child support). Keep these copies somewhere other than your house. (Perhaps with family further away?) Set up a new email account to only use to correspond with him - so you decide when you want to read messages. If you have a will, change it. If you don't, make one and clearly define what you want done with your estate regarding your children. Update your emergency contact list at work.
Fifth: Do not change the locks if the house is also in his name. Do not throw out/burn/destroy any of his stuff. Once he is moved out, if he leaves stuff of his behind, take pictures of it and send them to him, setting a date for their final removal, and tell him if he doesn't arrange for pick-up, you will do with them as you see fit, including possibly throwing them away. When you send this, do it in such a way that you can prove receipt of the letter.
Sixth: I wouldn't put him on blast publicly, but do inform your employer and your children's teachers what is going on, as this will definitely affect behavior in the coming months. Try and find a therapist to talk this through and determine your next steps emotionally. The amount of rage I felt towards my ex was scary, and I needed someone to help me process it and figure out what was healthy, what was not, and how to move forward. Listen to your kids when they act out about this, acknowledge their feelings (their world was upended too!), but do not dump on their father. I have never spoken ill of my ex -- I don't make up good stuff about him, but I don't tear him down in front of my kids either. (His behavior manages to do that for me.)
Also: I'm sorry to be blunt, but your husband has been abusing you. First by moving you far away from family and thereby isolating you, then by making you financially dependent on him by convincing you to only work part-time, and now by blind-siding you and leaving you holding the childcare bag. He is banking on you just curling up into a ball and letting him get his way. DO NOT LET HIM.
Once you have legal counsel set up, try to remove emotion from your dealings with him. From here on out, it's just business. He made the decision to send you a text instead of being man enough to say it to your face, so he lost the right for you to be accommodating and nice to him. You can be civil, but from here on out, you put yourself and your kids first. Fuck him and the horse he rode in on.