This thread right here is why you shouldn't post about bfing in aibu. Somebody will always post an insensitive and cruel post () and suddenly we're into accusations of bfing militia and ff equated to poison. It's such a false dichotomy and comes from how emotive bfing is as a subject and the statistical likelihood of there being one crass person on a thread of people trying to help. For once let's just accept that one person can have views which they express rudely and they don't speak for the majority or represent a 'cause'.
OP, I have an older child who started primary school when ds was 4 days old (he's 8 months old now) and there's a certain sadness about seeing their brave and weary acceptance of their new sibling and the demands they bring. I felt so very guilty about how good dd was about waiting her turn for my affections but I understand now with hindsight that it was a good thing in a lot of ways. She grew a lot emotionally in that time. She saw how important her tiny brother's needs were and I involved her as much as possible so that she was an ally, helping to ensure her baby brother's needs were met so that he could grow and thrive. And now that he can chase after her and knock down towers she builds for him and clap his hands at his brilliant big sister, their bond is extraordinarily beautiful. Because she appreciates the work that went into it and he appreciates her taking the time to get to know him as he emerged from the hellish newborn bit. You've given your child a sibling. The positives of this far, far outweight the negatives, despite what your hormones try and tell you right now.
I don't think a full switch to ff is necessarily the answer, not if you feel guilty even for thinking it. It does get better. Make sure you set aside time for your eldest on their own. I always made sure that in an evening ds was fed and clean and handed him over to dh so that I could bath with dd, read to her, do homework etc. If ds really protested then he went in the sling. In fact he lived in the sling for months and I managed to chase dd round the park, walk with her, read, play etc etc.
Have a bash at expressing and don't feel bad for having a glass of wine. I don't drink but friends who do have a glass of wine while bfing and are confident and happy with this. You have also given formula and know that ds will take it so there's no reason why you can't give the odd feed here or there if you want to.
But if you want to switch entirely then you do so. This is your baby and your lives together.
When I had my first I resented being chained to the sofa. But I hadn't really realised that I was stuck in a self-perpetuating circle. If I sat on the sofa with dd then all there was for her to do was feed. So she did. And I sat. And she fed. And I seethed. When I had ds, I was too busy with dd to sit. So I got up and put ds in the sling. And he fell asleep due to the motion or when a bit older he started looking around and being nosy and I felt more like myself, less chained, less of a machine.
The early days are hard, bfing or not. And we all feel guilty I think. I don't think reasonable comes into it. It is what it is. If I'm utterly honest with you then yes I think if you can find a way to make bfing work for you then that is probably the option to choose over a straight switch to formula. For all the reasons detailed on here. But it's about making bfing right for you, not doggedly pursuing it to the detriment of your health and familial relationships. There are choices involved in bfing, you aren't shackled to it. It's a relationship. You work hard at it, make a few compromises, stand firm on other stuff and hopefully enjoy it. If not you leave the bastard.