You have an ex who is a jerk, in the past he always played with your feelings as if you were a toy, and you will take revenge on him

"Why do you have to marry my father?! Just watch out, I'll make your child miscarry and I'll make you and my father divorce! Remember that!!" he said yelling at you

Yep! you married his Father because his Father likes you too, you can make Soowa miserable for the rest of his life because you are his stepMother and Soowa will have a younger sibling but he will do everything he can to abort you

You have to tell all these evil plans to his Father.