You have my sympathy, my wife and I separated in July after almost 20 years, we have 2 children 10 and 15, we also had drifted apart – I think pressures of work, raising a family and bills etc gets in the way. I have found it a real shock too as I thought we were forever though I probably buried myself in work – I have had several sessions with a Counsellor who has helped me come to terms that its not all my fault.
I’d recommend Relate as I have managed to get some form of understanding discussing this with them.