Thank you for reaching out to us.
For information on a potential independent residence permit after seperating from a spouse with EU-citizenship please see, for instance, this thread.One requirement will be that you are married for at least 3 years and living as married couple in Germany for at least one year before divorcing procedures start.
On your second issue: It is not possible to give you a general answer or advice, how to reunite with your partner and your child (living in Nepal) in Germany. Your chances will be related to your (then) residence permit, your income etc. You also need to be married to your partner.
Please don't hesitate to get back to us if you want to discuss your situation further.
All the best,