Selling Gifted Property

I am a Lady, My father willingly Gifted me the Ground floor and it is registered with registrar in year 2008 at that point of time I was unmarried but now I m married. All the utility bills like electricity water are on my name, even HouseTax is on my name. At the time of Gifting my father was having really soare relationship with my brother and wants to disowned him from all the legal assets and wanted to gift all 4 floors (all other floors are on my father's name still) on my name which I didnt allow him to do as 1 floor was n still is sufficient for me, But a year bk I got married and in the mean time he has change of heart and consoled with my Brother,his Son And know my brother is bad mouthing about me to my father who is more than 70 year old and bed ridden for more than 2 years, he is not mentally stable and still lives with me on my floor & not with his son, He gives his pension to his son but his son lives on separate floor with his family and had never takes any responsibility. Know both are threatening me and wants to cancel the Gift Deed reason becoz I Am Married now, though there are no clauses or subjectivity in the Gift Dead. My Question is that can they especially my brother can do so and If I want to sell the property then can I sell it. And can I tell or force my father to vacate my floor which is on my name ? Please give your sound advice And I will grateful of you. And would like to take your legal advice in future personally Regards Maninder.