Those situations where Talaaq takes place

Husband signing divorce letter

Q: In a heated argument with my husband, I wrote out a letter of divorce stating that he (his name) hereby issues me (my name) with a divorce and forced him to sign under his name. He signed in anger of what I was asking. I know that this is wrong. I would like to know if it constitutes to a divorce as I do not want to live in sin.

Divorce via sms

Q: My husband send me divorce on sms. He give me divorce not in front of me. He just write I divorce you three times and send to my cell phone number by sms. Is divorce valid?

Divorcing a pregnant woman

Q:

1. A brother divorced his wife once, a talaq baain, then performed a new nikah. After that he divorced her as follows:

I hereby formally issue one talaaq baain to ..., on 28/03/1439 (17/12/2017) at 15:22 pm. I also make ta’leeq of another talaaq baain which falls on 28/04/1439, exactly one lunar month from now, thereby completing 3 talaaqs, according to what has been mentioned as the sunnah method of divorcing a pregnant woman. Is this the sunnah method of talaq for a pregnant woman.

2. Is it not repugnant to divorce a pregnant woman? Are there any ahadith for this?

3. After 3 divorces, does the son-in-law have to observe hijaab from his ex-mother in-law and is communication permissible?