Hello ,
Answers to your queries below
First and fore most please note , its very easy to break a relationship, your husband may be cruel and causing great harassments to you, but analyze the reason behind and try to talk the issues out, remember you have 2 children, you need to be together for them. ELSE litigation is always Just A Signature Away.
1 and 2 . IF husband is threatening, to take children away, file a restrain order application under the domestic violence laws of the country you are in (as your message says you are in Vietnam ) In India an application u/s 18 of the Domestic Violence Act . You can also file an application under the Guardian and Wards act for the minor son for the custody of the children.
3. Mutual Divorce cannot be forced - All the terms of separation are pre discussed post which the Mutual divorce is filed. YOU dont want to give is a no option any further , IN case the lower court does not grant divorce to your Husband IF he files, the higher court will.
4. File maintenance application for yourself and kids (If you are gainfully employed than for kids only) - Let him take divorce , yu contest for your maintenance and alimony rights
Best of Luck
b.