I do get this OP. It can be hard. I've got 2 DC, 18 months apart, and became single with the youngest wasn't even 1. It was a whirlwind. Things are (slowly) calming down with 1 at school.
A PP was right in a way though, if you'd had another child, you would be dealing with it. Personally I found i had little inclination for mist things. Even down to bathing and washing hair. Once they were in bed,I justcwanted to either get stuff done or sit down in quiet. I certainly dobt gave the energy for much exercise although I would say I could do it after bedtime, honestly, i don't want to.
There are 2 of you though, so you should be getting some time. Your husband gets the commute to work and a lunchtime to himself. I cherished my drive to work pre covid.
You have to carve out time where you can. It does all feel like an effort though. It really depends how important it is to you . When my first DC was a baby I got in the habit where we wouldn't go downstairs til I was washed , dressed and presentable. It only takes 10 minutes,but I know from experience that if I didn't do it as soon as I got up, I could go all day unwashed. I still do that now, its our routine
I've recent started a proper skin care routine morning and night because I'm looking old. It takes a few minutes but the results are great. Skin looks so much brighter.
Clothes, well I'm not great at tis, but have bought a few things recently aseverything I was wearing was old and tired. Like me . So I do look a bit better in that respect. Just new jeans and a couple of tops. Also, new pjs so if I am lounging,I look and feel better!
Weight wise, it really is calories in vs calories out. The exercise most of us do, really doesn't use up too many calories. I generally don't do much exercise though am reasonably active through the day.
If its making you miserable (it was for me) just try to make small changes at a time.
I'm also 43, old tired and fat.