ur wife is involved in incest ?if thts wat u mean then OMG . . my suggestion to u is
1) secretly install SymbRECORDER software (30 days free trial ) in ur wife's nokia smartphone wid proper settings and record her phone calls . While she is busy in household work or in bathroom ,just transfer all recorded files in ur phone . This cn b a strong evidence . SMS is a tricky 1 as she might deny of sending any such SMS citing a reason tht my husband or sum unknwn person has sent them in my absense .
2) hire a pvt govt registered detective agency after u send her to her parents wid sum sweet words . They will record actual s*x act or physical intimacy betn ur wife and her lover . Court accepts such kind of strong evidences and nt just allegations either from ur wife or frm ur side . . Once u proove it then court reject any maintainece to her widout any delay .
3) prooving cruelty is a difficult 1 until and unless either u try for a fake sucide attempt and write her name in tht sucide note . Bribe police and get a FIR registered whr her name has put.it is risky altho as this cn backfire u and she may say tht she felt tortured due to ur sucide attemt. .
Dude , these kinda situations which u r currently in , are like a Chakravuha and U need to b strong Abhimanyu to crack it.