I'll give you all the advice you would have gotten from a variety of people, then you can decide.

Person 1: "You have got yourself into a tough situation. Things will only get worse if you hide that shit from Melissa. You should tell her the truth, even if the truth hurts. If things go downhill from there or their mom starts not liking you, at least you're not living a lie."

Person 2: "Just don't tell anybody anything. And make sure whatsherface keeps her mouth shut."

Person 3: "Melissa is perfect man, she is your best friend. Personally, I would stop getting with her sister and get back with her. The sister might seek revenge somehow and try to ruin your relationship, but you can probably work through it. If not, there's plenty of fish in the sea."

Person 4: "How smart are you? It would take a lot of skill, but you could pick the girl you want without hurting anyone's feelings, including their mother. If you want Melissa, slowly break it off with Angel very delicately. Make it seem like now that the situation has changed, you are being forced to leave her against your will. Get her on your side, be very apologetic and make her sympathize with you. Her cooperation is important. Tell her you are going to have to act like nothing happened between you and her when Melissa is around. At this time, tell Melissa you would like to be with her again. There is a chance the Angel will turn on you if she suspects that you were lying. From what you have said, it seems like those two aren't very close.

You need to set up a safety net by saying to Melissa that you would like to be honest with her and that you would feel guilty for not telling her something. Tell her that while she wasn't around, you got closer to her sister because of your sister and became good friends with her. Then, say that Angel started to like you, but you didn't share the same feelings for her and this made Angel upset causing her to have a bit of a grudge against you. If you do this, the awkwardness that will happen if all of you are together will not be out of the ordinary. Also, if Angel gets pissed off and decides to reveal anything about you and her, you can tell Melissa that she is lying in an attempt to ruin your relationship because of jealousy.

Does Angel's father know about you and her? If so, is he on speaking terms with Melissa's mother? Probably the best way to deal with that is to have Melissa tell her mother the story you told her about you and Angel. If the father says anything about your activities with Angel the mother will probably just think it was because you were close until Angel made her move on you. The mother will probably be on your side in this whole thing, since you would appear as though you are committed to Melissa.

If you want Angel, do something similar but the other way round and a little bit different. Make sure you take care of any gaps or threats that might reveal your true intentions."

Person 5: "LOL fuck em both man, more pussy is better than less pussy m i rite? m i rite?!? rofl"

Person 6: "... THREESOME! Is the mom hot? FOURSOME!"

__________________