dizzy, I just saw your post. I can relate in a way, when my four-year-old was born I really really struggled with breastfeeding. Not enough milk, came in late, he was losing weight... hospital had a go at me (well, in my sensitive state it felt like that anyway!). I just felt dreadful. I was devastated.
When he was 4 days, I bought a bottle and some formula as I didn't know what else to do.
The next day, my milk came in. I mixed fed him in a deliberate pattern for the first month (so my supply wouldn't go), then pretty much only breastfed him until he was 6 months and mixed fed again until he was 13 months (breast and bottle). I thought - in the beginning - i'd never be able to do it. And also suffered mastitis and then thrush. But it did work out and he wasn't confused by bottle / nipple and my milk supply didn't dry up.
That bloody pump! I hated it! I've decided I'm not getting one this time and torturing myself with it.
I just wanted to add that so you'd know that it DOES get better.
BUT you don't have to breastfeed, just do what works for you. Formula is amazing stuff. And know that if you do give your little one a bottle, it isn't the end of breastfeeding (I thought it would be).
At this point, you need to be kind to yourself. It sounds like you're having such a hard time 