In most cases you would call him by his name. You do not share a common ancestor, so aren't really related.
You still call your brother, your brother.
You can call your elder brother as 'ANNA' and your younger brother as 'THAMBI'
You would call your husband's younger brother a brother-in-law.
Your son will be a nephew to your brother, and will call him "Uncle".
what i call my father elder brother's wife
Brother
Brother
Would you call your brother god?
The relationship of the sibling of your sister-in-law or brother-in-law to you does not have a name in English. You could call them your brother- or sister-in-law if you want, or you can call them the brother or sister of your brother- or sister-in-law.
You call your husband's senior brother simply a brother in-law. There is no difference whether he is a senior brother or a younger brother he remains your brother in-law.
Your husband's brother is your brother-in-law.
Brother in-law.