Roopa consumed phenyl last night, hours after her husband, a medical shop owner, was shot dead by three motorcycle-borne men near Raj Talkies intersection in the district, police said.
Roopa and Vivek Singhal got married on December 4 this year.
Roopa was rushed to a private hospital in the district and her condition is stated to be critical, SHO Deepak Sharma said.
Meanwhile, the SHO said that police teams are screening details of all mobile phones used for incoming or outgoing calls near Raj Talkies intersection at the time of the attack.
Local shopkeepers held protest and shut down their shops.
Four police teams have been formed to work out the case, the SHO said, adding several possible hide outs of the assailants have been raided.