There doesn’t need to be a drip, it’s right there in the OP. She is working a “big job” but also doing 70% of the housework. That’s a lot.
@WhatIsAScottishEgg
I could have written this exact post 5 years ago. Many things can be true at once. The first step is to talk to your husband about sharing the load. If he is as great as you say, then he will understand and start picking up the slack. Be specific, hand over tasks that would make your life easier. E.g I need you to cook 4 times a week, you need to do the school run, vacuuming is now your job, you do it twice a week etc. More likely it’s the mental load that’s causing a problem, hand that off to him.
You do need to see a GP about your mental health. For me the catalyst to do so was anxiety, but the medication has definitely helped my mood. Looking back, I was sliding into depression. Medication has really helped.
Once those two things are sorted, you will be in a better frame of mind and able to assess your relationship. When I was in the same place as you, my relationship was my target, because it was the only thing I could control. He was the reason I was unhappy and leaving to find me, and maybe someone else who was more, I dunno, exciting, would fix my problems. But having thought about what I have and where I am, that’s not what I want. I’m happy with steady, I don’t need someone else. I need my husband who bumbles along in life, is a homebody, enjoys the same thing I do. He isn’t whisking me off for romantic weekends or telling me he loves me every day. He is making me laugh, he is doing a load of little things which shows he loves me. That’s what I want and need. That’s what makes me happy. I carve out “me time”, I protect it, I take it. That really helped me too.
It might be for you, that isn’t enough. And that’s ok. You don’t have to stay, you can leave for you. You will be a better mother to your daughter if you are happy.