I have no doubt your in laws will cause soooooooo much trouble for you if you live together with them. They will act like they are the head of the house, and you are the alien. The relationship between you and your hu*****and will be much worse.
I suggest you keep your job, because you have more power when you have financial freedom. It is good to be stay home mom only if you have a good relationship with your hu*****and, only if you two cherish and support each other. But at this moment, the relationship is a little shaky.
I suggest you try really really hard to find a good daycare (and a babysitter that can help to cover the hours that you are not available). It will work out. You will spend more money and do more babysitting work, but it will be so worthy, because your in laws won't control and manipulate your life. Don't be naive and assume maybe it will be ok to live with in your laws. It won't! According to what they did so far, not a chance to live happily together with them, even you keep your head down. I mean, no matter how nice you are, they will be mean to you anyway.