Please rephrase your question.
Ignore and forget about it and don't say a thing to him about his son.
Well why would you want to ignore him?
Forget, ignore, neglect...
forget, neglect, ignore
Forget, Negect, Ignore
When they forget that they don't like you and try to talk to you, you ignore them. When they try to be mean to you, ignore them. Ignore their body language to you.
get a new boyfriend
If you are intended to have an intercourse (even with your boyfriend), firstly I've to tell you that you are entirely risking your virginity. It is strongly recommended not to have any sexual relationships before marriage. Probably, the persuasion of your boyfriend might be the reason for your intention. In that case, both persons should not forget or ignore to wear protection.
ignore him
jealousy?
I'll ignore him.......
Ignore her, and tell your boyfriend to ignore her. If he won't, dump him. Too many fish in the sea, and you deserve better.