Becomingless - I had PND after each of my three dses, and I am sure that what I saw at the time, and for ages afterwards, as my failure to breastfeed, contributed to my PND - so I can really sympathise with what you say about breastfeeding being so important to you.
Have you considered mixed feeding? Some formula feeds and the rest breastfeeds? I did this with ds3, and it enabled me to carry on partially breastfeeding for twice as long as I had managed with either ds1 or ds2. I breastfed him during the day, and his last two feeds - the early evening and late evening ones - were formula - and this worked really well for us. He slept well, my supply was able to build up again over night, and I felt good because I was carrying on breastfeeding for longer.
The other thing to remember is that, in the grand scheme of things, whether your baby has breast milk or formula is not the be-all and end-all. How you nourish your child is important, of course - but there is so much else that you are doing now and will do in the future, that will impact hugely on your child's development.
As another poster said - soon you will be weaning. You will be able to be creative about the weaning foods your baby has - with ds1 I spent a day each fortnight or so making a variety of different purees, and freezing them in icecube trays, so that I could take out a variety of different things and he could have a meal that was, for example, pureed cod and potato, with parsnip, carrot and broccoli purees, or lentil and rosemary puree, with a variety of veg purees. I wasn't this assiduous with ds2 and ds3 - I lacked the time or the energy - but for them, I used to puree the food that I was making for dh and I, and for their brother/s.
You will spend time feeding their minds too - reading to them, playing with them, doing arts and crafts with them, choosing the right schools for them, helping them with their homework and spellings, reading through their Personal Statements for their UCAS forms. You'll enable their social lives - asking friends with similar age babies around, going to baby groups, taking them to their friends houses, picking them up after parties (sometimes the worse for wear, in the later teenage years).
You will make sure they get plenty of activity in their lives - playing chase with them, teaching them to catch a ball and kick a ball, taking them to the park, teaching them to ride a bik, cheering from the sidelines as they play games or do Sports Day at school, driving them to and from sports practice, buying kit - and laundering kit - the list is endless.
What I am saying is that, right now, how you feed your baby seems like the biggest thing in your life, but even if your baby never had another breastfeed, there is so much else that you can and will do to help them grow up into an amazing adult.
I saw my inability to breastfeed my babies as a huge failure on my part, and I beat myself up over it for years - but now I look at them - two are away at university - ds1 will graduate with a Law degree this year, and ds2 is in his second year of a 4 year Maths degree - and ds3 is in his final year of school, and is likely to be offered an unconditional place at university to read Geograpy - and they are all healthy, happy, well-adjusted young men who work hard, play hard, have lots of friends and are capable of living independent lives, so I think dh and I have done a pretty good job, despite their lack of breastmilk.
I do also think you should cut your dh a bit of slack - he sounds as if he is doing lots to help you - and holding down a job at the same time. He is certainly doing a lot more than some men do - if you really had a man-child, you would be doing all the housework and cooking as well as doing all the baby care and feeding.
He's not perfect - none of us are. We all make mistakes, or miss a bit of food on something when we are washing up - it really is easily done, especially when you are running round keeping the house going and looking after your wife, so she can nurture your baby.