my best friend of 11 years broke my trust and I don't know what to do.

Recently my (24F) best friend (22M) has confessed his feelings for me for the 3rd time. The first time was over a year ago, we both confessed that in the beginning of our friendship we liked each other but as our friendship progressed I thought it was best to only stay as friends so I never brought it up. We didn't think of it to be a big deal since we are only friends and there was no romantic feelings anymore (or at least on my end), and agreed to never speak of it again. The second time around was a few months ago, he brought up again that he has liked me in the past and that id make a great wife, but again I told him we are only friends and that's as far as it will ever go. This third time, we planned to go to eat and he ended up planning a date. Coffee, museum, & dinner. It felt odd to me because we only agreed to dinner but I went along with it but I admit I felt slightly uncomfortable because I felt like I was deceived into a date I never agreed on. We were driving an hour away from my home so I couldn't just leave even if I wanted to. Throughout our conversations I hinted that I didnt appreciate when Im friends with a man and I move with the intention of us being friends and he moves with the intention of dating. My gut knew what was going to happen. At dinner he confessed that what I had said left him thinking. He said he wanted to be honest that he has liked me multiple times throughout our friendship. I told him I didnt want to have this conversation again, it was going to turn this dinner awkward. What set me off the edge was when he told me that we are adults and should be able to have this conversation. I told him that this was the literal 3rd fkn time we have this convo and I have already set my boundaries and made myself clear. This was no longer appropriate and as adults he should learn to respect peoples boundaries. He apologies but I told him that if he felt he couldn't sincerely be my best friend then it's best we break it off and I will respect it. I felt so uncomfortable, and I was silent the entire ride back to my house.

I don't know what to do, ive asked him for some space to think because im so upset. For these past 11 years we've had such a great and genuine friendship. I have never imagined never speaking to my best friend again but I feel so disappointed, deceived and betrayed. is it possible for our friendship to move forward as only friends? Should I break it off even if I don't want to? How much of our friendship has actually been genuine?