I'm a virgin, but had sexual activities. my ex could insert his finger up the front vaginal wall touching my g-spot, could my hymen be broke?

Hymen: Yes. If you had an imperforate hymen then you would already know by now (as you are a menstruating women).

Unlikely: Most women don't have a hymen that breaks. Very rarely, women have a hymenal remnant that is like a piece of tissue that stretches from top to bottom or side to side across vaginal opening. Most women do not have a hymen that will break with fingering or intercourse. It's a bit of a myth. Almost all women have a ring of elastic tissue around the introitus, but it's not like a curtain.