How can I come to terms with my guilty feelings about quitting breastfeeding?

I too was struggling with breastfeeding. Each feeding time was a nightmare and both baby and myself would end up frustrated and crying by the end of it. It felt worse because my supply was low even though I ate all the milk boosting foods that are recommended and pumped every w hours. I was tired, frustrated with myself, angry at myself and I often cry during feeding/pumping. Within 2 weeks, I fell into post natal depression and started ignoring my baby when he was crying. Thankfully my sister was around to snap me out of it. I realized as much as breastfeeding has it's own beneficial benefits against formula milk, it wasn't worth the stress and frustration. I should have been happier and enjoying and experiencing the newborn phase. I switched to formula feeding ever since then and never looked back. There are of course relatives that nagged at me about being selfish for not breastfeeding but I turned a deaf ear on them. For the meaner ones who usually are farly- related from me, I'd usually "offer my son" to them and ask them to breastfeed instead. It's harsh, but I get my point across.