I think what's people are posting is because the op and her dh made choices. Financially they chose to get a bigger house, now. They are choosing to save for nursery now. They knew there was another child they were financially responsible for.
I am sorry op is feeling low. But she is asking a finance related question, people will question her finances. The decisions they made aren't wrong. But they are their decisions.
Tbh I find it very difficult to believe that they have no spare cash at all, that they couldn't even put £10 away a month to save towards some second hand furniture.
If they can't, they must have known that when making the decisions about the mortgage, having a baby, saving towards future nursery fees etc.
If getting stuff for the house is a priority for the op, they need to review their finances. They, may, need to lower their expectations on what quality they can get, or get second hand. It may take time to save. But it's definitely not a situation where they can't afford it or can't even understand how other people can afford it.
I bought a sofa with my exh. It was the first new proper sofa we had. I was 34 when we got it. It didn't fit in my new house after the split. My Dp has it in his house. He is moving in with me and it's going to his sister's. It's just what people do.