The only way to solve the problem is if Manju gives them permission to move which (knowing her stupid mind) probably won't happen. Ideally, the Sethis should break off the marriage as it's not fair to Vishal to have to marry the obsessed psycho that Milli has become. We know they won't do that either to keep their izzat blah blah blah.
Abhi should slap Milli hard, avoid her as much as possible, and either try to get Milli married off quickly without having to lie that he loves her or leave with Simi quickly. The problem is he will try to handle it without involving anyone so then when Milli tells them all that Abhi said he loves her or they hear him saying it, no one will believe he just said it so that she would marry Vishal. You don't do stupid blackmail where marriage is concerned anyways. Milli has gone from my favourite female character on KB to my least.