Below is the Judgment details, which says Talaq is Valid, If Few conditions meet.
Unilateral triple talaq must be preceded by attempts at settlement and be for a reasonable cause.
(Shamim Ara vs State of U.P. & another AIR 2002 SC 3551, SC)
(Dagdu Pathan vs Rahimbi, Full Bench of Bombay High Court,2002)
**In your case reasonable cause could be filing Criminal case against your husbad
Husband's second marriage confers right on first wife to live separately and claim maintenance.
(Begum Subanu alias Saira Banu and another vs A.M.Abdul Gafoor AIR 1987 SC)
Triple repetation is not a neccessary condition for irrevocability of effect of Talaq
(Saleha Bi v.Sheikh gulla, AIR 1973 MP.207)
The wife's presence is not necessary it may be signed in the presence of Qazi or the wife's father or any other person.(In Re, Raja Saheb,44 Bom.44.)
In your Case you can only Haraass him, But I believe If he able to proove his Talaqnama, which was possible Serve to you and Once prooved then it will weak your case.
in the end, you can file for Post Divorce Benefits under Muslim Divorce Act 1986. to Claim your maintanence. which I think Court will direct him to pay you once he prooved his divorce