i am a guy 50 yrs old. i write to get some guidance on the following: (there is alot to share but i try to summarize...)

my wife (she is 46) is depressed/at a lost because she (and her siblings) feels that her mom has been 'monopolized' by an outsider. her mom claims this outsider is a 'god son.' her mom tells them he treats her well.

my wife and siblings used to spend regular and extended time their mom. in the last three years those time spend together has decreased rapidly to once a week, once a month, and now even down to only may 2 hours... because she needs to meet with the 'god son.'

my wife and her siblings have spoken to their mom - but seems all dialogue have been futile. when my wife told her mom she doesnt feel the love anymore, her mom replies she loves her alot.

some bkground on the guy(i hear this from my wife and siblings): am told he is gay; about 40 yrs old; his boyfren died about 3 yrs ago; he doesn freelance courier svcs; he doesnt spend time with his own mother; he claimed to hv converted to catholic faith; he is now going to marry a divorced muslim woman; he calls my mom in law at odd times in the night; even asks her to go along with them on honeymoon.... and alot more weird and unacceptable events, etc

over the past 3 years ago hearing about what was happening, i felt he is some kind of 'conman'. i havent yet prove it. when i asked my wife to engage a PI to check on this guy - they refused...

my wife is depressed... i have been surfing the net to get some perspectives on all this but no luck. i have ask my wife and siblings to see 3rd party - maybe psychologist or priest but they refused...

i hope if you reading this you can kinda get the picture... can you help or direct me to someone or some source/agency...

i am asian chinese. i lived in singapore.

thank you so much for reading this. i do need some help.

Gosh, what a terrible dilemma you find yourself and your family in. I'm afraid I have no direct experience in this so my support can only be from an intuitive perspective. It seems to me that your first port of call should be to the man himself. Can you appeal to his better nature, explain that your wife and her sisters have lost a major part of their relationship with their mother and that they believe he can influence an improvement? Of course, if he is a con-man as you suggest this may all fall on deaf ears.
If all else fails, and your mother in law contimues to rely on her relationship with this man, the only thing you can do is support your wife in a positive way. Perhaps she will have to come to terms with the fact that her relationship has changed permanently and that she may have to make peace with that outcome and any other resuting consequences.
My very warmest wishes are with you. I hope you find a way of moving forwards.