Do you do the right thing?

No. Do things right

The right thing to do is to marry and make an honest woman out of your teacher. But while you do have a crush on her, you're not sure whether it would last long. Besides, there famous relationships that didn't last long, so there's no guarantee about yours. You're also couldn't be sure that you wouldn't be swept off the feet by another, probably younger, woman later on. Or maybe Siew Chew would loss the mood for sex since she had achieved what she wanted. Maybe as they say, men tend to reach full emotional maturity between the ages of 40 and 43, and your just 18 plus years old.

So maybe you can't marry Chai Siew Chew, your teacher.

And she did say that she is okay with that.

Anyway, while you wouldn't marry her, at least for now, what you can do is be a responsible father for the child currently growing in her womb. Thanks to your earlier manipulation with the Rulebook, you have legitimately made enough money to be considered wealthy, and can certainly pay for child support. In fact, you can buy a big house, fully furnished and with full complement of workers to attend to your needs and hopefully, your family.

So, if you want, you can ask your teacher to stay with you at the said house and have her needs taken care off. Of course, that will keep her away from other men, just like you want, and allows easier for pre-natal and post-natal care. But, if you take that move, there will be no hiding the facts that you're rich, and you knocked up your teacher.

The other option is to let Siew Chew stays at her house and you provide the nurse and caretakers to take care of them.