Tough
Ok sorry to hear about your situation , however it is one which is becoming more common these days due to property prices.
Firstly did your Dad leave a will ? You said that your Mother did intestate (no will).
If your dad left a will he no doubt left everything to your Mother and your family would have no bones about that (i hope).
The issue here is firstly how many are in your family , brothers and sisters ?
No matter how well they are doing they are still entitled to their share. But the process is such , since your Mother did not make a will all siblings are entitled to an equal share of the property , this is done by taking out probate. An executor needs to be appointed to lead the closure of her affairs , i suggest you do this straight away and name yourself , this is important. This is a process whereby all her affairs, bank a/cs , loans , stocks, including her home are assessed and passed by Revenue . Depending on your Mothers life this could be complicated or simple.
What is left after Revenue deduct any unpaid tax etc... which is not common is divided equally amongst your family.
However a letter is initially sent out by the solicitor stating that they are entitled to X amount.
Now your family can choose to accept this or they can also waive their right for natural love and affection of their brother and to also carry out your mothers wishes.
But you will always have one or two who will not tow the line. If that is the case do not get into a legal wrangle , sit down and work somethiing out , remember you own a share of the house already so deduct that from the current value.
Then try to reach a settlement with your family , get a valuation done and also estimates on the contents.
To be honest it all hinges on money , sad to say but that is my experience.
But please get a good solicitor , do not pick one out of the phonebook , get one by reference who specialises in land law, succession as you never know what lies ahead.
There is another route , if you stayed in the house for another 6 years and no one claimed there right to the property who could progress a claim for Adverse Possession , look it up , interesting point of Law.
Let me know how you get on !!
But do not start something until you have covered all angles , for example if you just stay there and say nothing , what will happen ? Probate costs about 3K so you will need this is you are to become executor or agree a split with you family , but that's where the testyness starts.