As you can see from alot of posts that after you quit to be a Stay At Home Mum, either you will love it straight away or you might take awhile to get used to it. But to me from what i read from yr posts, i feel that you shpuldnt have a problem adjusting to it.
Since yr family is finanically stable and yr husband salary can support the whole family then resigned and take care of yr baby full time. You will love it. Seeing all the first times of yr son.
I would have really like to be a stay-at-home-mom to take care of my children and watch them grow. Sigh.... But not alot of us are so fortunate.
Also since you have a high-rank post that means you have alot of experience so most likely, if you found staying at home is not yr style then you should be able to get a job easily. So you still have a safety net there.
If yr husband agrees and feel that it is best for the baby then quit and take care of yr baby. Dont let yrself get so stress up that you miss the good times with yr baby. Plus in yr suitation now, yr relationship with yr husband will take its toll because you will hardly get time to spend together.
But in the end, it is up to you. What all of us are saying is alomost the same. Take care.