Friend help, How do u help someone without telling them what to do?

[Valentina V]

Ok, here's the thing... My fiance's friend of 13 years is having alot of issues. I want to give my fiance the best advice, or help him help his friend somehow discretely.
Now, his friend has three kids with this woman,they live together, along with her own two kids from another father. (all kids are ranging from 2-6 , twins n rest not) Anyway, so they just moved into this new apt, its very spacious and nice. Already 2 months in there, they are not picking up after themselves. There is literally dirty clothes all over the floor, unwashed dishes, multiple rotting garbage bags still not taken outside, also they have two dogs in the back of the apartment. When u walk in there it smells like socks and garbage and musky odor. Its really nasty. My fiance is embarrased to say anything.
He recently got laid off and she doesn't work. She is also bipolar. The kids are fine, they eat, and get taken care of, also the dogs are good too. Its just that their parents are not taking care of
of themselves. Their grown adults and their not acting like it!! Their literally pigs! Already they trashed their home and kinda just sit in it. Its not healthy..He doesn/t want to embarrass his friend by asking him, but how can he do it?