Yes, it's called being in a different location and not answering her calls.
We've had this conversation before OP. I have no idea why you thought it would be a good idea to move in with someone who terrorised you when you were a vulnerable child. Whatever those reasons were, it's triggering you daily. You are already traumatised from a decade in an abusive marriage and now you are being triggered in another home further compounding your trauma.
Can you make the connection with your anger and difficulty in healing and being back in the house with someone who abused you as a child?
I don't understand what is going on with your IDVA. If it's as you say and, despite knowing that you were abused by your mother, they advised you to move back in with her and stay there until the issues with the family home were resolved - they are doing an appalling job of helping you. I would make a complaint and try to get another IDVA. I cannot imagine someone who specialises in abuse telling a traumatised client to move into another abusive household when they have already been diagnosed with C-PTSD. I can only assume they're nuts and can't be trusted.
Your IDVA should have been able to advise you on housing. However, you're saying that they haven't which doesn't surprise me since they seem poorly trained and irresponsible. Therefore, contact Shelter who should be able to advise you. You would feel safer in a location unknown to your ex, at the moment you are on egg shells knowing he could turn up at any time.
You can't heal while you're in a house that's constantly triggering you. It's impossible and it was a really bad idea to move back in with her. I understand that you were perhaps fleeing your abusive ex but that was a while ago now and you've had time to research other options.
Your options are: 1. Approach the council, tell them you have been left homeless after fleeing domestic abuse. 2. Find somewhere to rent privately, even a house share is better for you than where you are. You are not safe there mentally or physically and you won't start to heal there.
A refuge is somewhere you flee when you are trying to get away from an aggressor. A refuge is a safe space where the location is unknown to your aggressor and it has trained workers there who can advise. I wouldn't suggest going to a refuge now. I would when you first left rather than going to your mother's but not now. Now you can use the internet and make calls and find somewhere more suitable to live.
OP the reason who are struggling so much is because you are living with an abuser. Just because your mother is no longer driving at walls in order to terrorise you, doesn't meant she's changed. For the sake of your physical and mental health you need to move out and find somewhere else to live.
I'm not sure what the 'legal' issues are regarding the house - how hard is it to divorce and sell the place? People do it every day, what's the hold up? What are you trying to achieve through the courts?