Feeling so overwhelmed

I’m 34 weeks pregnant on my third, my eldest is 3 and youngest is almost 2. I feel awful but I am getting so fed up of the daily battles with food (not fussy eaters just need a lot of effort) plus having to think of what to feed them (I do a weekly tea list but I means snacks and lunches etc plus finding the energy), entertaining them, mum guilt, listening to bickering. Their dad works Mon-fri and might be home to see them before bed, but his dad recently had an accident and now every other weekend he has to help them cut grass because he dad can’t do it anymore. I feel like I am constantly trying to find 5 minutes on my own. We’ve all got covid so have been unwell but my partner is in work, because there’s jobs he can do on his own. This week has just really hit me. He’s feeling frustrated because he has to work, and thinks I’m annoyed at him because he has to work, I’m not, I’m just annoyed at being by myself all the time. My friends have all got their own kids but I haven’t got the energy to deal with other kids or anything anymore. To be honest I don’t know where I’m going with this, I just know i feel stuck in a rut, on my own and im going to have a newborn on top of this in a few weeks.. If im struggling now, how will I cope in a few weeks? How can I divide my time between three little ones without completely burning out? Plus house work (hubby is good with helping when he’s not working but it’s not the same). Totally feeling overwhelmed and need a week holiday on my own (then I’d probably cry after one night and miss my kids completely and feel guilty 🙈). I’m just so done in, and no one gets it at all because I’m always the strong one who just gets on with everything so it’s easier to brush my feelings under the carpet because I’ll just get over it 🙄