Next of kin.

[Denisdiamond]

Although I have been married for 36 years and have 2 sons of 36 and 29 years of age , I have been separated for 20 years and have been living with another woman foir that length of time. Who is my next of kin /

[dzug]

For what purpose?
For most practical purposes it is your current partner but if you haven't divorced your first wife she (and your sons) would inherit if you died without making a will.

[dot.hawkes]

I think if you made a will and left provision for your partner you would be fine, but you need to set things out with professional help to ensure your partner is not left in a vulnerable position