He has 2 adult children but did not have a will.
If he did not have a will, you most likely do not have any rights as an heir of the estate as you were not together long enough to have established a common law marriage. If he had a will, he could have named you as a beneficiary. Check to see if a will exists. You may have some rights as a tenant in the property-you should check local laws and contact a local attorney.See question