OP you need to take this one step at a time, otherwise it's overwhelming.
You need proper legal advice which you can obtain from Rights of Women. This is to find out about your rights in the event of divorce and what to do about the house. You can also ask about the divorce papers.
You need emotional support so I suggest you look into finding out what is available in your local area. You can find your local domestic abuse organisation here. See if they have a Freedom Programme in your area or something similar. They may have free legal advice clinics so it's worth finding out what's available.
I also suggest that you find out your local authorities' domestic abuse number.Just go to your council website and look for their DV services. They tend to be joined up so they can give you advice regarding your home at the same time. If you can't find it, then call them. You need to find out about your council tenancy in the event of divorce and they should be able to tell you. Dig out your contract to have at hand as they will ask you about it.
Your son's anxiety may be partially caused by your relationship with your husband. You may find it gets a lot better once he's settled after you split up. There could be other help available and it doesn't sound as though he's been properly diagnosed. You could contact the National Autistic Society as a starting point and they will hopefully guide you to a solution that works.
Gingerbread can give you advice and information on being a single parent. Child contact, maintenance, benefits, education etc
Sort out the above first: legal rights, housing, emotional support, son's diagnosis etc You don't have to do anything yet, but this is taking action and making a plan which is empowering in itself. This has been what's been holding you back and preventing you from committing. Once you have a plan in place and the right support, you'll take that leap.