You may have to tough this out. My oldest son was given a bottle when I was transferred postpartum by my midwife for emergency surgery. He had to have something, as it was obvious he had low blood glucose. I was too out of it to say no bottle. Oops. But we fought nipple confusion, which is what you have here, for weeks after that one bottle I ended up saying no bottles, despite what everyone around me was saying, and spent a lot of time crying along with him and eventually overcame it. He nursed for 2 years.
I hesitate to suggest a nipple shield, but sometimes that is a good interim step.