2. 该不该告诉他我们为什么离婚. 是因为他爸爸出轨, 把妈妈辛苦赚来的钱花在别的女人身上, 妈妈受到很大的伤害,不得不离婚.-- No.
3. 如何和孩子谈离婚的事? 不知道如何开口, 要谈些什么,重大点有哪几点? -- 10 yrs old understand what is divorce. tell him the fact, and regardless of what, you love him. And it is not his fault.
4. 怎么阻止LG抹黑我的言行? 还是听之任之. -- I believe action speaks louder. Kids are smart enough to know and to tell. Love your son, and treat him as before.
5. 如何消除他的言行在儿子心中造成的负面影响? -- again, action speaks louder. you did a good job so far by not put any negative comments about his father. It is not easy, but it is best for your son.
2 things to keep in mind:
a. from your post:昨天我妈告诉我, 当她给儿子说, 爸爸不要妈妈了. I would tell my mom, not to say such thing to my child. it does not help the current situation, yet hurt a son's feeling about his father.
b. Talk to school, ask for school psychologist or school counseling service. They will not tell kid, but will keep a close watch for you when he is at school.
Bless.