Contact Women's Aid or your local DA charity for help OP as you sound like you need real life support.
I talked to my GP about needing to leave as my marriage was impacting my physical and mental health and they referred me to a social prescriber who was very good as my point of contact as I had no privacy from Ex except during medical appointments. SPs tend to have an office at the surgery because of this.
Mine helped me with MH support and doing phone calls to the local da charity, CAB for benefits and housing rights, and came with me to a solicitor appointment as I was in such a mess at the time, but you might be strong enough to do those by yourself.
Decide on what you want to achieve, seek outside support and guidance (or clarification) for those wants, and break down each bit into sections and make step by step plans.
Divorce - the admin, the financials, and the children.
get paperwork together for his, yours and joint finances.
Housing - sell house (and find out your share via a solicitor).
Look on rightmove for rentals.
Talk to the banks about mortgages.
CAB - help with benefits and housing costs.
Solicitor - to find out your rights and to sort out the financials.
Mediator - for the children.
CMS - for when you have split, if the children stay with you more.
Break it down into bite sized chunks then slowly cross each one out as you progress. As long as you keep moving forward the nightmare will eventually end. I'm still not divorced but I'm in my own home and it's so lovely. Far better than I ever imagined.
Edited because MN formatted it in a stupid way.