Is the HELOC a community debt that can be allocated in probate court so that I am only responsible for half of it?

Boy, did you get tattooed here. Obtain the services of a beneficiary litigation attorney who can bring a probate action against the executor/administrator of the estate to challenge the disposition of the property and the liability allocation for the loan. Unfortunately, your position is not good if you do nothing, and the bank can foreclose; if the property is not yours, you may want to let the bank foreclose.

The loan is secured by the house and those should go to the same person who gets the house. But there is a reasonable chance to shift the burden to those getting the business if you can argue certain items were purchased exclusively for business purposes and no personal use could occur and it was intended that money generated by the business would be used to pay the HELOC. You basically would be saying that you borrowed money to lend to the business so the business has to pay you the full amount back. I doubt there are any published case decisions on this topic. You could google it yourself to see if you can find something. Have you tried telling his heirs and seeing whether they would compromise [who ends up with the business. If his other heirs are adamant and/or a substantial amount is involved, go see an experienced probate attorney who would know if such a prior case existed. In interviewing several probate attorney about whether you will hire them, you can ask them if the argument is reasonable. I suspect that you and your husband never considered the problem, but if all moneys earned were put in one pot or he was the only income earner your position would be stronger.