winning defamation case against false 498A

As you said you  are acquitted from 498a then you have valid ground for filing defamation case. As far as time is concerned it depends upon the court where case is filled and how case is presented.

You can maintenance form under section 125 of Crpc.

You can file Perjury section 340  crpc.

Winning defamation case is very difficult thing to do. You can file a case like suggested above. But results are gauranteed only if deposition of OP defames you. Here you need to establish that you are famed person.  Then comes defaming.  The extent of damage to your public image will be the damages you seek in the case.  To what extent OP damaged your image, that is what you have to prove. Talk to advocate locally regarding this, better to talk to old advocate who knows your case better.