Should i take an emergency pill if my bf fingered me and i'm not sure that he had pre-cum or semen on his hand--happened on18 n' my period due date-20?

No: At that point in your cycle the risk of pregnancy is low but it sounds like you should be talking to someone about starting a reliable method of contraception .

Morning after pill: To be safe I think you should take the emergency 'morning after' pill. If he had semen on his finger and then inserted it in your vagina there is a very small chance you could get pregnant that way.

Protection: If not ready for pregnancy – use protection every time.