Can husband still file for divorce if I am not wiling to divorce him?

The divorce laws depend upon the religion of the person. Assuming you are Hindus, you will be governed by Hindu Marriage Act.

Section 13 of the Hindu Marriage Act which covers divorce has been reproduced below for your better understanding.

Section 13(1) states that a petition may be presented by either the husband or the wife, for dissolution of marriage by a decree of divorce on the ground that the other party-

i. has, after the solemnization of the marriage, had voluntary, sexual intercourse with any person other than his or her spouse; or

a. has, after the solemnization of the marriage, treated the petitioner with cruelty; or

b. has deserted the petitioner for a continuous period of not less than two years immediately preceding the presentation of the petition; or

ii. has ceased to be a Hindu by conversion to another religion; or

iii. has been incurably of unsound mind, or has been suffering continuously or intermittently from mental disorder of such a kind and to such an extent that the petitioner cannot reasonably be expected to live with the respondent. Explanation.- In this clause,-

a. the expression" mental disorder" means mental illness, arrested or incomplete development of mind, psychopathic disorder or any other disorder or disability of mind and includes schizophrenia;

b. the expression" psychopathic disorder" means a persistent disorder or disability of mind (whether or not including sub- normality of intelligence) which results in abnormally aggressive or seriously irresponsible conduct on the part of the other party, and whether or not it require or is susceptible to medical treatment; or

iv. has been suffering from a virulent and incurable from of leprosy; or

v. has been suffering from venereal disease in a communicable from; or

vi. has renounced the world by entering any religious order; or

vii. has not been heard of as being alive for a period of seven years or more by those persons who would naturally have heard of it, had that party been alive.

So as per the above mentioned Section, your husband can seek a decree for dissolution of marriage (divorce) on any of the above mentioned grounds, even if you do not agree to the same.

He may seek divorce on the grounds of cruelty (mental or physical) being inflicted upon him by you. 

OR as you have stated that you and your husband have been living separately for past one and a half year, so he may even file a divorce at the end of 2 years of living separately stating that you had deserted him for a continuous period of 2 years.

We suggest that in case you do not want a divorce, and then file a petition for restitution of conjugal rights under Section 9 of the Hindu Marriage Act. 

Section 9- Restitution of conjugal right: When either the husband or the wife has, without reasonable excuse, withdrawn from the society of the other, the aggrieved party may apply, by petition to the district court, for restitution of conjugal rights land the court, on being satisfied of the truth of the statements made in such petition and that there is no legal ground why the application should not be granted, may decree restitution of conjugal rights accordingly.

We also suggest that you should file a criminal complaint against your husband under Section 498A of the Indian Penal Code and under the Protection of Women from Domestic Violence Act in the nearest Police Station and the Crime against Women Cell.