Leaving baby overnight?

Ladies I'm looking for a bit of advice please, I had my darling baby boy 5 weeks ago today (valentines baby!) - my MIL has been dying to have baby alone since I had him, she wants to take him for walks without me or have him for a few hours to "give me a break" - I haven't agreed to that yet but today she said that I really need to get to a point soon where I can leave him OVERNIGHT with her because otherwise I won't be able to return to work in January 2017 as my boy will only want me, she said my health will start being affected by the sleepless nights (baby feeds every 2hrs) and eventually my marriage will start to suffer as my husband and I will start bickering... But I just don't want to leave him, I can't bear to be without him for even a minute - I tried for 8 long years for this baby and ended up having <a href="https://glowing.com/glow-fertility-program">fertility treatment</a> - I don't even let my hubby take him out without me just now. I need advice - am i making things worse for myself in the long run? Should I start letting go soon to make it easier later or is it still to early? I'm starting to feel like an overbearing parent but I just want him with me???
Update: thank you so much for all your input - I feel totally relaxed with my decision to wait now, I think the tiredness was starting to make me doubt my own judgement - baby will be staying with me until I feel 100% comfortable 😊 xxx