Not married legally wife is asking maintenance after 11 years

She can claim maintenance from you and also for child , and if you want to settle matter out of court then consult ADV. and then only go for settlement. But the crux is whether you were already married before you and your so called wife were in a relationship and was marriage performed by Hindu rites and ceremonies like saptpadi?

what are u decided first
u r both r residing separately then what u have separation, divorce or restitution.
there is legal way of maintenance and in case u r not maintained her otherwise property attached of ur share.
u r prove that ur wife is maintain herself

Yes legally she can ask you for the monthly maintenance and also a property which is in your name. You can not skip this easily. It's very serious matter. No matter u have proofs of your marriage or not. Further you can contact me.