Speaking from experience, my dear, the best thing you can do for both your and their peace of mind is to move. In my case, i lived with my brother who had a wife(3yrs older than i am) and 3 kids. The complaints varied from me 'talking to the kids anyhow' to me being 'too quiet' to reducing food portions​ and so on.i stopped eating 2 months after i got there. A friend gave me keys to his apartment which was empty, still is but i felt it would be disrespectful to leave my bro's house​and just​ move to somewhere which was in same estate although i do my cooking there and relax there sometimes​. The woman kept complaining to my bro about the most insignificant things and one night, she got confrontational and attacked me saying that i was disrespectful to her(note that by this time, i had started leaving the office at about 8pm, would get home by past 9 just to avoid this woman and most weekends were the same) the confrontation led to an arguement and she attacked me (by attacked, i mean, she physically lunged at me as i tried to walk away from a pointless arguement about nothing but her ego). To my utter shock, my bro joined her and started beating me.this was around 11.30 pm. By 12am, my things were outside the gate, packed by my bro. I had to physically carry all my bags to my friend's house which was about 300meters away. The next day, i saw the rest of my bags etc close to their bin. She already asked the help to clean out the room where i had stayed. I laughed at her insecurity and carefully packed my stuff and tossed their key at my bro.
My advice, if the woman is insecure and you can play the fool, buy the kids gifts, buy food etc, gist with her often etc, it might buy you some time in the house and if you can't, you just have to leave. There's nothing you can do to please her. If they're not too financially okay, if she sees you looking good everyday, she'll probably start getting jealous(if insecure). In my case, this woman's friends kept firing her up, telling her they can't allow a grown relative stay with them bla bla. I was really disappointed in myself cos i gave myself a short time to be at theirs but u know how money issues get and i got completely broke while there. Life gets like that sometimes. I regret that i didn't move immediately my friend gave me his keys and allowed the matter to deteriorate to what it got to. That relationship is broken for life.