Can anyone help. Status changed to widowed but long separated (19 years). Income now being calculated as married but no access to his income. What to do?

You would be considered to be widowed if you were never divorced so you have to indicate the change in marital status. If in fact he/she is deceased.
If you're having an issue with the spousal amount, you can just enter a figure in for your ex's income that will remove it - like $30K.