milkyman, just telling yourself not to feel bad, or even hearing people say this to you, is prob not enough :(
Is there someone you can talk to, who will listen to your feelings about this, and help you make your own decision and feel strong and confident about it? I think it will help if you work out what it is about breastfeeding that you feel you/your baby will miss out on if you stop.
If it's closeness and contact, then you can formula feed skin to skin, you can feed responsively and flexibly, and you can be the main/sole feeder while your baby is small. With those aspects in place, you will mimic some of the nicer aspects of breastfeeding.
If it's being in tune with your baby, then being pain-free and comfortable while formula feeding will help with that.
If it's the health aspects, then paying careful attention to preparing the powder milk safely will help minimise risk of gastro/infection.
You may not have to stop entirely - it might be worth thinking about retaining some breastfeeding for as long as your milk lasts. In any case, if your baby latches at all (sometimes babies do this better when sleepy, or you can try co-bathing and see if your baby latches on spontaneously), then you can continue putting your baby to the breast even if there is no actual feeding :) ). Or you can express for a while.
Yes - your mental health and well being are part of being a mother to your new baby and your first child - and if it's important for you to retain some breastfeeding, then this might be an option to consider. If it feels better to stop entirely, then think about the ways to make formula feeding closer to bf.
I hope things work out for you.