What happens next? Can anyone help?

Hello,

I'm new here but have been looking for some advice regarding pending court case please. I have navigated my way through a difficult divorce settlement without a Solicitor as after a few letters I realised I could not afford this. We got the financial remedy from courts stating that I have to sell family home but the kids will stay with me as I live near their school and have always been responsible carer. However since the order landed my ex husband has taken my 16 year old to live with him 15 miles away and now I have just received court summons regarding younger son of 14. My ex has made false allegations of abuse in order to get this to court without any mediation.
My question is what do I do next as a litigant in person. I have no means for legal representation as I am trying to buy a new home and also now paying maintenance to my ex for older son even though I am still paying for mortgage on FMH and have part time income. My ex is a coercive bully who has set out to destroy me financially and emotionally and in his words leave me homeless. Yes, awful I know, but.... there are many reasons why he shouldn't get custody of my younger son but I don't know how I get my side across to courts. There is no information about how I respond to his allegations or whether I just show up in court for the first hearing with some written notes in my defence or do I have to submit something to the court beforehand?
I am really confused and exhausted from it all but obviously I do need to defend myself and my children from all this. Any advice what my next steps should be most welcome. I have tried to get legal aid and been to Citizens Advice already.

You can book a free consultation to discuss child issues - not my area of expertise I am afraid.
There's also a comprehensive guide in the guides section that you may find helpful.

Hadenoughnow