Pam is completely wrong in asking R to leave N and kids alone. Its not like Ragini is forcibly after N and kids, feelings are mutual. Pam can give some thought to N and Agham-Suhaan's feelings if not Ragini's if she geuinely loves them and is bothered about them as she frequently claims. But her current actions are defined by pure hatred for Ragini and not concern for Neil. Not denying her love for her brother but at present its all about her own self for her. She is being plain selfish in a negative way and mean.
And how and why will she lose the kids if NR get back together. I'm sure Ragini has no intention of replacing Pam in their lives. Pam can still continue being their mother but she is insecure and wants to be their only mother and not share the kids with Ragini.
I do give credit to Pam for being a mother to these kids when their parents went on a self destructive mode but what she has turned Ranbir into doesnt speak too well of her skills.
I really dont want this character to turn negative but she is on the path already. And i too thought in the beginning that perhaps Pam fears a repeat of what happened 15 years ago with Neil and Ragini and its purely concern for Neil which is making her fear their reunion but as much as i wanted this to be the reason behind her actions unfortunately it doesnt appear to be so.
I have zero sympathies with Pam at the moment.