Calling Ma/Pa

i am divorced. I have a child. From now onwards how do i regard my in-law? Do i still need to call Ma/Pa?? If they invite me and my child, we will go for reunion dinner. If they dont invite, do i and my child must attend?? How much hong pao do i need to give to them and little childrens?? If i go only reunion dinner, is it ok to give hong pao to in law, oranges and goodies? Why i asking because i dont wish to attend rest of the days. I am not closed to them where my child is also scared most of the time when they come and visit my child once every 2 months?? Hong pao how much i give, as i am the only breadwinner for my child. Hoped someone can let me know. As i am not chinese but my husband yes. I dont know what to do?? Please help.