She is not ready to l divorce me...can I file for annulment of marriage or a contested divorce?
If you can establish that you were forced to marry her against your wishes and that you cannot continue with this married life which was thrust on you by using blackmail tactics etc, you n file a petition to annul the marriage by a decree of nullity.
I have a flat in my name...she knows about it..home loan is going on the property..can she claim stake in that flat?
No she cannot stake any claim in it as a right.
Can I gift the flat to my mother and pay the emis thereafter on my own?
Yes, you can do it there is no legal infirmity in it.
Can she claim in my ancestral property?
No she has no right in it.
I am a govt. Employee...I have declared myself unmarried at the time of joining,which is untrue.....can this declaration render me dismissed from the service?
There is no such thing that the marriage shall affect your employment.
What if my father disowns me
There is no legal term called father or anyone disowning their relationship hence it makes no difference.