Just a perspective from the other side - my son could not go to sleep on his own until over 2 and was a very frequent waker in the first 18 months. But.... now he's a joy to put to bed. Honestly, some days, it's the easiest thing we do all day. It all passes in time. Being there for them now, when they need you, is worth it. It's hard right now - I know! - but right now you are helping them develop the ability to self soothe by building their sense of security and wellbeing.
Being there does not mean mum has to do 100% - that's physically not possible a lot of the time, so it's important to make sure you have several adult helpers and get time to yourself as well.