Yes. I know and understand she also blames Fred. Fred is honestly as much of an asshole as Jason, just whinier with a large portion of holier than thou. None of that explains why she (Melissa) is suddenly spotted twice in the QoS bikini and seemingly fully "corrupted" as this game seems to be defining it.If you would pay attention while reading, Melissa (judging by parallels from other paths and what she said and how acted on this one) blames for her boyfriends cheating not only Jessica, but also Fred. In other paths she is more... vocal about it, but in this premise is the same, and she want to have revenge on them too. As we see in this one, she spotted a lot of times with Jessica, and they tell us they put aside their differences. This is just 70% of the full update, and there is still time for an explanation, but we can assume what they will plot something together, for one reason or the other.
Regarding her outfit - yeah, imo there were a lot of misses in regard to chosen clothes, no defend for this one, but again, we know what Melissa pretty much corrupted by Jason a long time ago, so not that surprising tbh
Hell as the story has been set up, Melissa basically should be trying to avoid everyone at this point because she can't trust any of them. She blames, partially, Jessica and Fred, Jason and Junior were her blackmailers, Johnny was the one that cheated on her, and Cami, Ruth, Eddy, etc. all have close relations with people she already feels have betrayed her. She literally can't trust any of the main cast.