If she had a will it will need to go to probate, in fact it should have gone to probate after her death! If she had a living trust and beneficiary directive ownership goes directly to those people named in the living trust.
If she did not have a will or a family living trust then the estate will go to probate but likely money from assets will go to a trust for their 11 year old child probable if these two were not married administrated by one of her parents or sisters / brothers.
He may want an attorney if he felt he should get something from her estate and they were not married but then that will start a court battle over “Claim” to a portion of the estate which will potentially drag this thing out.
There is no need for you to talk to an attorney as this guy does not have the legal authority to sell this house, if this woman had no will or living trust it will likely be sold by a trustee of the court for a reasonable arms length sale. Although it is a possibility that the judge will just convey the home to this woman’s living parent (s) or living sibling (s) who would become the trustee for the child’s future.
If they were not married and / or this guys name is not on the deed, then he has nothing legally to do with the house.
Back taxes are not good as this house could be lost to tax sale and should have been probated or taken over as beneficiary of a living trust a few years ago.
A living trust does not cost a dime to administer assets by her trustee, a probate with a will, will probable take about a year to settle and if she died without a will it could take 2 or 3 years to settle.
He could be in violation of state or federal laws for not probating or settling her trust right after her death as their are legal ramifications concerning state and federal taxes, creditors, her name on open credit, debt incurred, or back taxes owed.
Considering he is the boys father I am surprised he did not do what was required as soon as she died, I suspect it is because he would no longer have the house to live in and because of finances chose to ignore probate laws.
He can not settle anything unless he has a will in hand or which was placed with an attorney, otherwise her family Dad, Mom, Sister, Brother, etc. needs to probate her estate. I wonder what happened to any creditors she had at her death, they could now be owed thousands of dollars in interest and penalties!
I would run from this if I were you, the house positively will not be sold wholesale unless he is in possession of a will?