It's been 3 months since my husband told me that he wants to divorce me. It's been 3 months since my husband told me that he wants to divorce me.

As a stylistic point: we often would say 'he wants a divorce'.

BI had hoped that, by giving him some space and time , he willmay/would recover from his emotional exhaustion. I had hoped that, by giving him some space and time, he may/would recover from his emotional exhaustion.

As you say 'I was wrong' in your next sentence, I assume that you hoped or believe that he may recover.

Lst night he suddenly pushed me to agree an earlier divorce within one year, even though he agreed before that he can/is willing to wait for two years, so that I can have permanent residency in this country to keep my job my career. Lst night he suddenly pushed me to agree an earlier divorce within one year, even though he agreed before that he can/is willing to wait for two years, so that I can have permanent residency in this country to keep my job my career.

Mainly stylistic.

He said that he haves been dating for 3 weeks now and hethat he has met some great girls. He said that he has been dating for 3 weeks now and that he has met some great girls.

He feels sad that he haves had to reject two girls' dating invitations because he can't be honest with themand admit that he is still in a marriaged. He feels sad that he has had to reject two girls' dating invitations because he can't be honest and admit that he is married.

This is how I would say this. Ordinarily you would said "I am married, he is married", rather than "I am in a marriage."

He said he doesn't want to scare them, also he doesn't want to have any risk to hurting other girls. He said he doesn't want to scare them, also he doesn't want to risk hurting other girls.

Why did he tell me theseis? Why did he tell me this?

I told him before that I don't want to hear anything about his new dating planlife because I want to set a boundary so as to feel safe. I told him before that I don't want to hear anything about his new dating life because I want to set a boundary so as to feel safe.

'Dating life' is the standard phrase.

He knows telling me these things would hurt me, but he still did it anyway. He knows telling me these things would hurt me, but he still did it anyway.

I assume you wanted to write "he knew telling me THIS would hurt...", but "these things" is also correct as he has told you a number of hurtful things.

He cares anbout everyone except me. He cares about everyone except me.

Why heHow can he ignore our 7 years relationship and keep hurting me like this? How can he ignore our 7 year relationship and keep hurting me like this?

Why do I even believe that he loved me? How could I have ever believed that he loved me? Why do I even believe that he loved me? How could I have ever believed that he loved me?

Your sentence is grammatically correct. I have offered an alternative below which suggests that you cannot believe that you ever felt that way.

Why has my kindness becomes my a weakness that he can use it as as leverage? Why has my kindness become a weakness that he can use as leverage?

Stylistic

I still don't understand that how much a person can change their behaviour so much when they are in love and withoutnot in love. I still don't understand that how a person can change their behaviour so much when they are in love and not in love.

Small changes. "So much" at the end expresses how much he has changed, whereas your original sentence suggested that you actually do not know how much a person can change (as a general concept, like it is theoretical).