Hi there and thank you for your question,
I will try to assist you with your legal question but please feel free to ask as many follow up questions as you like until you are 100% satisfied.
The only way that she can stop you from coming back to the house, is if she applies at court / police station for a domestic violence protection order against you, on the basis that she needs to be protected from you due to emotional or physical abuse that you levy towards her. It is a 2 step process; the first step is she deposes to an affidavit and the police give her an interim protection order; the second is to go back to court (and you can appear) and then she must convince the magistrate to make the interim order into a final order. You would obviously have the opportunity to argue why it should be refused. Everyone can have witnesses to testify. e.g. Bob saw you hit her. Harry took her to hospital for the assault.
If she doesn't do the above, there is no way that she can keep you away from the house. The house is partly yours, and you are entitled to access to your property. Also, you work from home.
I suppose my advice is that if you are physical with her, or threaten physical violence, then it will make it MUCH easier for her to "kick you out" through a protection order - since one of the orders contained in the protection order might be that you are not allowed within 500m of your house. i.e. you are forced into moving out!
If my answer hasn't answered all of your questions, please send me a REPLY with follow up questions so that I can continue to assist you in this same thread for as long as you need. Let me know if you need more advice - dont just rate my answer as "bad".
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Good luck and best regards,