Don't be so sure that 佢哋一定幫我, at best they may just help the 孫, not you, although it's not your fault.
My husband also had an affair with a girl 2 years ago. My 9962 also pretended to help me :;pppp: , but in fact they just helped their son, not me.
If I were you, take good care of yourself & BB. Prepare 2 plans, one is if he wants to come back later, can you forgive him?
The other plan is if he decides to leave, what would you do? Prepare options/back-up plan for yourself & BB. No matter which plan you will use, try to get as much money from him as possible because you have BB now.