lai lai share more specific story, then only can advise

best is don't stay together in the same house

Don't stay at the same house.
Ask your hubby to get a house. few block away.

from your husband perspective though, you have to understand that his mom is the one that has been there and caring for him since he's small.. so need to be patient and compromise a bit.. there's this saying, you don't only marry your partner, you marry the whole family.. but at the same time your husband must also defend you because you're his partner.. just that he needs to be a bit tactful.. like my mom and fiance also dont really get along well, but i told my fiance, understand my mom can be a bit annoying, just be patient and compromise for a while only while meeting her.. because in the end, we don't always gonna meet her since i already bought house far away from my parents

Conflict with in-laws quite a common topic.

There is another option. Why not you try to "bribe" your MIL out of this. "Bribe" can be by giving some benefits to achieve mutual win-win scenario. If you know she like something, try to "bribe" her heart.

Life is short, don't go against each other, if she willing to cooperate, both you & her can have better days.  She "make" her day, you "make" your day, there is no need to go against each another.

As one of the forummer said.

Move out.

I did. So much better. In my case is my mum. Everything is others fault and not hers.

Now she is almost begging me to move back in which I refused.

Good ruck to her

The one way is for me to shut myself mentally when around her when living together.

It does make the message go across. Only talk when the matter is important.

not trolling but i would be thinking to get diff husband.
u see life is short. 10 years will go unnoticed. and if by then only want to open new book/chapter, 10 years of life wasted already.
and only another 10 years remaining ( im talking about youthfull life) of course one might live until 70 but i personally think 55-70 not prime anymore.

should really embrace the life of 30-50

done tokok

Yep.

Since its your house. You have a say in house matters. Don't ask her for opinions. Your house your rules.

Done.

You got kids already?
You will need her help with kids.

Liek I said.

There are times you will need to put your foot down.

And again all the best to you.

No easy dealing with all these people.

hopefully 5 years or shorter. sometimes this type of people hard to go one. plot twist we go first before them 

She can't. Technically the husband & wife already moved out & staying at their own house. The MIL now come to stay with them because the FIL already passed away.

If the old people really talk don't want to listen, be friend with them they don't appreciate & kwailan abit some more, they will find soon themselves the path to old folk home, that will be the usual stories public get to hear. Then what comes next will be the story about the char siew children alleged for mistreating their parent for sending them to old folk home.

The ending need not have to be such sad, go negotiate the better ending with the MIL. Not worth for such ending.

The best fate arrangement you could wish now - some neighbors / relative son send their parent to old folks home because the old ppl too kwailan. That incident will become a lesson for your MIL to tune down.

The son have to stand up  PERIOD

well
hope there's equivalent phrase 'dont stick your dick in crazy' for you case
i stand by living meaningful life.
of course theres ups and downs in life bla bla bla.
but it's important for each person to evaluate which ones they are willing to confront

If I were in your place, if it were to happen to me. These should be the sequence of options:-

1 )Try to befriend the in laws. She goods, I'm good, everyone happy. If bribing her can do the jobs, I won't mind spending the cost.

2) If option 1 don't work, second worse scenario. The in-laws do her stuff, don't encroach the boundary. As long as she respect that boundary, that will do.

3) If option 2 don't work, 3rd worse scenario. Vent it out. There is limit on each one can take, instead of complain direct to your husband, just get into direct fight with the in laws, if need to shout just shout. If she don't want to see this scene, ask her to better behave, if not, you just need to make sure you is the devil that she will regret to provoke. The eldest DIL is bad, send 1 signal that 2nd DIL is worse if she continue to be kwai lan.

4) Look for the old folks home, sign her up. Call the eldest son, each family to share the expenses.

This world, people fear the ruthless & bully the kind ppl.

If possible, there is no need to go till option 3) & 4). The best case scenario is 1).

This is actually a life circle.. we grew up.. we go to school .. we found a partner .. we start a family ..
yes normally the ladies will complain more than the guys because normally the wives follows the husbands. being a husband also isnt that easy because if the MIL and wife doesnt click, he will then have to handle two women very tactfully
now.. as we grow older.. we will too have kids.. and our kids starts his or her family. same situation if you son brings home a wife that you cant click.. then the table will be turned around.

yes. i have encountered this with my grandmother. she too was very toxic until the extend with a temper. so my dad and his siblings decided on moving her around families. that was how extensive the problem was and i remember the siblings having regular meeting to discuss before finalizing the plan to move my grandmother between houses. i cant remember how many month or months with each house. maybe this can be an option for you to try discuss .. but if the house belongs the your MIL.. then I think my option is not viable.

So it's just 2 sons or she has more kids ?

if it's your house, why not ask your parents to stay for a few weeks to "help with the grandkids" ? then your MIL can go back to her elder son.

obviously plan ahead so the situation is not heated, maybe just awkward so when MIL feels out of place she can find friends/her own siblings.

but she has her own place to stay ? if yes, persuade her to move back and arrange MIL own sibling / children to visit on a schedule ie Monday Eldest son , Tuesday 2nd Child etc

may need to get part time help / maid for her and everyone chip in for the cost or tapau food when visiting so not a burden to host so many "visitors"

Your then future mother in law potential behaviors' (now legally mother in law) was made known to you 15 years ago. 15 years ago & you decided to proceed to get married ~ you decided to accept the flaws. After you accepted the flaws, now you suddenly you cannot accept it, 15 years time not sufficient to prepare for today?