Hi there. I have only just come across this thread and can see that you have had some fantastic advice already ,
I know exactly what you are going through and have been through it myself. Xh walked out suddenly last Feb, came back for 6 weeks, left again at Easter. I discovered he was having at the very least, an Emotional Affair with his best mates wife.
I wrote XH a wonderful letter, telling him how lovely he was and how much I loved him, because I thought he was having some sort of breakdown. He led me on for a few weeks, then wrote a nasty letter back - "the house was a disgrace" was one comment...... well he lived here too..... Ignore your MIL. I rang mine and said that I was devastated and how could he just walk out and she said "these things happen" like it was totally normal. No support for me at all. If they are not going to support you, then dont include them in this situation, other than to look after the children.
Even after getting the letter, I begged XH to come back. Threw my dignity out of the window because I loved him and wanted DD 4yo to grow up with her dad around. I have been to hell and back emotionally. Im still not out of it yet totally, but understand that is normal from what I read on here.
I lost 3 stone in as many months as I was physically unable to eat. I went onto antidepressants, rather than let me DD see me crying all the time. I couldnt stop shaking.
BUT - it is the old cliche. It really is only time that can make a difference to the way that you feel. In the meantime it is a rollercoaster of emotions that you just have to ride and deal with.
I got fantastic support on here. I went against what everybody said because I wanted to do everything I could to "save my marriage" but XH had already checked out emotionally and it was all pointless.
You do need to get legal advice, go to the council etc, rent, council tax, explain what has happened. Try and get them to help you to sort it all out and to get everything into your own name. You need to freeze all bank accounts, so that any unused overdrafts cant be spent by him. Go and see CAB for advice, see a solicitor.
If you have a Sure Start Childrens Centre near you, then approach them for help. They usually have somebody clued up on benefits and they also offer free counselling. You must have a child under 5 to be able to use their services.
I divorced my XH last year. He left in April, we could have divorced in August, but I left it til the house and everything was agreed. I divorced him because he said he no longer loved me, because he had cheated on me and because I was afraid he would get into debt. He has since amassed thousands of pounds of debt, in less than 12 months.
I don't want to upset you, but it does all shout OW, so please build yourself up, stay strong and be prepared for anything to be exposed.