Who is legally intitled to our house?

The answer to your question depends upon how the title was held and who died first. If your brother died first AND the property was held with survivorship rights, then the property became the property of your mother and would be disposed of under Texas intestacy laws. Assuming that your mother only had three children, the property would pass to you, your sister, and your brother's children (not the wife- she wouldn't inherit from your mother). If your mother died first and the property was held with survivorship rights, then the property would be disposed of in your brother's probate proceedings. Under that scenario, the property would be distributed to his spouse or children (depending on the requirements of Texas law, which I am not qualified to discuss) and NOT you and your sister. If the property was held as tenants in common, then each of your mother and brother owned one half of the property which is required to be handled in their separate probate estate proceedings. At the end, if my math is right, your brother's children/spouse would have 1/2 of the property, your brother's children would have 1/3 of 1/2 interest (from your mother), and each of you and your sister would have a 1/3 of a 1/2 interest. Which brings us to the question of how you are going to sell this property. It appears that nothing was done to transfer the property at the death of either your brother or mother. Hire a probate attorney to figure this out and get the property deeded to the appropriate persons and especially to deal with the spousal rights of your brother's wife. Then, all of those persons would have to sign the contract to sell the property and the deed to the property. This isn't a matter of how to divide the proceeds. It is a question of who owns this property and in what portions. Get a lawyer.

Assuming the property is located in Texas, Ms. Akin is correct, although joint tenancy with right of survivorship tends to be rarely used in Texas (for anachronistic reasons). The answer is a bit more complicated by community property law, which is why you are really going to need to look closely at the deed to your mother and your brother with an attorney. Assuming that there are no rights of survivorship, your mother died prior to your brother, she was not married at the time the property was acquired, and you had two siblings (mentioned) who survived her, you and your two siblings would have inherited her one-half interest in the property when she died - i.e., at that point, you and your sister would each be owners of 1/6, and your brother would be the owner of 2/3. In this situation, when your brother subsequently died, his 1/6 interest inherited from your mother would be his separate property, and his surviviving spouse is entitled to a life estate in that 1/6 interest with the remainder passing to your brother's heirs on her death. How the 1/2 interest that your brother acquired with your mother passes would depend on whether that interest was acquired during the marriage with community property (and if so, whether all his children are also the children of his surviving spouse) or whether the interest was acquired as his sole and separate property. (The language in the deed is critical here.) In any event, you, your sister, and his surviving spouse will have two procedural choices at this point: (a) a declaration of heirship (for one or both of these estates); and/or (b) filing an affidavit of heirship in the real property records (with respect one or both of the estates). Have I convinced you that you really need to see a probate attorney to work this out? I recommend thaty you try to find somebody in the county where your brother passed away or where the property is located.