Why do I have to give up helping my family to help my girlfriend?

Then she's being selfish, and manipulative. Any mature girl would know that family comes before a girlfriend. You two are not married, if so, then the priorities would be different, and if she still threatens you by saying she's getting a so called sensual massage from a male figure, call her bluff and leave her ***. You're mature enough to straighten priorities, so you need a girl that's more mature.