Advice on my boyfriend hating my mums new partner

My mum has had a new partner for the past year which my boyfriend (baby’s dad) does not like atall which has resulted in my mum never getting the chance to take baby anywhere as she is always with him. This means I don’t get a break as she apart from my boyfriend is the only support I have. She has asked multiple times to take him out whether that be the park, zoo or just for a walk but as she is mostly with her partner my boyfriend will not let her. This obviously upsets my mum as it’s her first grandson but when I mention to my partner that she said it would give us a break he replies with “I don’t need one” forgetting about me and if I would like a break some days.. my boyfriend is quite hot headed and if I say something out of line he will get quite angry so I have to be careful with what I say so I’m just looking for some advice please 🥺 he is so against my mum not taking him anywhere because of her partner but his parents aren’t really involved as they live about 2 hours away so this is also frustrating for me as atleast my mum is trying x