<human>: My mother and stepdad have been together for about 7 years. During my actual parent's relationship, my mum and stepdad were sleeping together for 17 years behind my dad's back. Eventually my family broke apart, and then my mother and stepdad got together. My mother is not the easiest person to live with, she has OCD and is very set in her own opinions, and the stepdad is definitely going through the classic mid life crisis at the moment, wanting freedom and to be young again.

Anyway, fast forward 7 years, my stepdad has been contracted working overseas in Saudi Arabia now for about 6 months, every 8 weeks he comes back here to Australia for 12 days and then goes back to work. It's been a rocky few months with them, they had the make or break talk about 6 weeks ago, with my mother declaring everything she was unhappy with, and it seemed that stepdad just folded to all of her demands. One of which is planning on selling their house and building a new one.

Recently, while on facebook, I noticed a post from my stepdad to a lady who lives in Bahrain, which is where he goes on the weekends from work. It was obviously meant to be a private message, but some old people are still learning about that. Well, this message consisted of things like "I've enjoyed spending time with you while I'm here, and I'd like to see you again." and it finished with "I miss you."

I couldn't believe what I read, and silly me didn't take a screenshot. An hour later he noticed what he did and it was removed off facebook.

With my stepdads history of cheating in every single relationship he has had, and the fact that my mum and him have not been very stable the last few months, I'm thinking he is cheating on her. And I do not know what to do.

Should I tell my mum? Confront my stepdad even though I have no evidence?

Can you condense the text into a few key points?
<bot>: Stepdad has been working overseas for 6 months, accidentally wrote a private message onto a woman's wall which I saw, and then deleted it. He has a history of cheating in relationships.