K-1 Fiancee Visa. I like another man. Please advice!

Hi, I was in the US about a year ago for about 2 month, met a few people and made friends. One of them asked me later if I'd like to be his fiancee, I agreed, and he applied for K-1 visa for me. It took some time but documents are in the embassy now. But that's how it works - it's either nothing or everything. About a month ago another man I met in the US got in touch, says he thought about me all this time and wants to do K-1 petition. I like him much better, he is about my age and I feel we are much better match. I really want to get married long term, not just to come to the US. What will happen if he applies for my K-1 visa too? Can I cancel the first K-1 application? I haven't been on the interview yet. Thank you in advance.