What would you do in her position?

o.k. my sister and her girlfriend have been hiding their relationship from their parents.....for about 3 months now.... well my sister told our mom she had a boyfriend (total lie) and her girlfriends parents have no clue she is gay... well had no clue... and on saturday her mother(sister's girlfriends mom) walked in and caught the two making out... and all hell broke loose she started crying and everything!!! my sister is only a freshman so she can't just buy an apartment .... they say they're going to get married in 3 years BUT it's hurting the family... kinda like romeo and juliet except two juliets... im o.k. with it as long as they don't have to much PDA around me... what should she do?