How do I introduce.......?

[rufusredcoat]

My mum and dad were married for 45 years before my dad died 5 years ago.
My mum remarried a couple of years ago and they are coming to visit us soon.
I have known my stepdad since I was a baby (family friend) and love him like a father but do not want to call him dad.
I am 29 and wondered what be the most appropriate way to introduce him to people.
Would I say "this is my mum and stepdad?" or "this is my mum and... (his first name) ?"
or some other way?
Please dont say call him dad.
I was very close to my late father and do not want to call my stepdad this.