I think this is one for Legal, and for Relationships.
What a frightening situation for both you and your daughter, OP. 19 is so young; it's going to take her a lot of courage to accept that she married a controlling man, and to step away.
The best thing you can do is to listen to her, and encourage her to talk. Do not give advice, do not tell her how awful you think he is or how vulnerable you think she is. Just keep asking her open questions ("who - what - where - when - why" rather than "yes - no" questions), as realisations are easiest to come by when they come out of our own mouths: so the more you ask your daughter about her day to day life, the more she is likely to realise that it is not healthy or normal, as she hears herself describe it.
When she is talking to you, validate her feelings. "Oh poor you!", "That must feel so lonely", etc. Show her that it's ok for her to feel bad about her living conditions: she is being made to normalise things, to think that all this is normal and ok. If an outside person validates her hidden, niggling doubts that her living conditions right now are not ok, it will strengthen her resolve to eventually leave.
The key thing here is that she has to choose to leave for herself: tempting as it is, you can't swoop in and save her. The first barrier to ending an abusive and controlling relationship is the victim's vested interest in believing it's all ok, and hanging on to the hope that it will get better. The mental work of accepting that it is a controlling situation that won't change and that she can't tolerate is work that she will have to do for herself, in her own time. The best way you can help her get there is just to listen, and validate her feelings.
Legally, there is probably a lot more you can do re: the bogus visa application, but that is not something I have any knowledge of, sorry. Do try Legal though.