Mil has health problems and I believe mental health issues. ( Poss agrophobia but as she will not go to doctors nothing can be diagnosed). She is only in her mid 60's but never sets foot out of the house , which suits fil as he has a hobby which involves him being out of the house most of the time and going away a couple of times a year with "the lads" also in connection with his hobby.
Anyway , about a year ago mil received a letter in the post telling her that her husband was having an affair ( I suspected it may have been the ow trying to get my fil to leave). Fil convinced her it was somebody trying to cause trouble and it was never mentioned again although I have to admit my dh and I both believed it was true.
Then a couple of months ago fil was having problems with his phone and he asked my dp to look at it. Up popped numerous photos of a naked woman, possibly taken on one of these so called lads holidays. Fil looked embarrassed and tried to explain it away by saying a friend had sent them to him in error!
Then tonight my dh went out running, decided to do a completely different route and spotted his Dad's car in a country car park. His Dad lives nowhere near us, they don't have a dog, why on earth would it be there? Dh hung around the car park and fil appeared out of the woods, obviously surprised to see his son and said he had been out jogging! What?! He is in his 60's and has never been jogging as far as we are aware. Dh reckons if he had hung around long enough he may well have seen a female following my fil out of the woods.
I am in a dilemma. I get on with mil and know she could not cope if she knew my fil was up to anything. I know all the above facts are not concrete evidence but have to admit all put together they do not look good. I would never ever say anything to her, if anything it would be up to my dh, and I know it is none of my business but how can I look her in the eye and in fact my fil too.
Advice please.