Good advice. Resist the temptation to avoid all pain and begin a new relationship, or continue the old one, with deceit. There are conseqences to that we dont even fathom, even if we never get caught. There is no feeling like being upfront and completely honest with whomever you are with bor. If either girls is that special dont ruin it by having a pointless lie sitting between you the entire time.
And if you are caught, you will have irreevocably destroyed whatever bond you had with either. The relationship might continue, but it will never be the same