Custody of 2 month old?

[Stuck33]

Am a regular but have NC'ed for this
I have a 2 month old baby with my partner and things just aren't working out between us. I want to try relationship counselling but whether he will is a different matter. He left his email logged in on my laptop and I saw emails from his mum telling him to go to a solicitor to find out his rights regarding custody.
DS is EBF and I have no plans to stop anytime soon. How would custody arrangements work? I can't bear the thought of being apart from my baby, it breaks my heart. What would happen if we were to split up? There's no way he could be taken off me is there?

This is kindly meant from an old hand...
First take a big deep breath... what your partners mum says and what he thinks might be two different things. And anyway, everyone should know their rights, it doesn't mean he's planning to take the baby necessarily.
Then both of you stop thinking about yourselves and what you want as individuals and focus on what should want for your baby... two parents who can share his care in a sensible and kind way, whether that is together or apart. You are the adults and you need to sort yourselves out so that he can have a happy life wherever.