Seeking advice and help in cofounder conflict

Hello,. Nischal Nayak here. I'm not sure if it's right to write here, but I don't have anyone in my network to reach out to, Here's the situation: I'm building xflow, a real-time payment app for international tourists. Initially, I was working as a solo founder and tested the product in India to gather user feedback. I was also looking for a co-founder on the Y Combinator co-founder matching platform because there was too much work for me to handle alone. Just four months ago, I connected with someone, and at that time, I wasn't making much progress on anything. So, I accepted this person to help distribute work. I would focus on building the product, and he would handle distribution, sales, and raising funds. Over the past four months, I've been trying to figure out how to test the product at scale in Thailand and India. Since there aren't many tourists in India, it's easier to test in Thailand. About a month ago, I met someone who was very interested in the idea and has been instrumental in helping us test the product in Thailand. This person has also been helping us connect with investors, craft the pitch deck, and create reasonable financial projections. He's enthusiastic about progressing quickly and has even started discussions with banks for potential collaborations. He's accomplished more in one month than the person I connected with four months ago. The individual I partnered with four months ago has been slow to act and hasn't put in enough effort. He often claims to understand the business better than I do and criticizes my attempts, saying I did things wrong because I don't know what I'm doing. However, he hasn't made any attempts himself and claims to be investing time in devising a proper plan. When I try to address this issue, he ignores the conversation and insists that I will understand later, refusing to explain. I believe in the philosophy of building and testing quickly to make progress. The person I met one month ago has been actively contributing and forging valuable contacts. Building and testing an MVP for enabling payments in Thailand wouldn't have been possible without his involvement. Now, there's a conflict between the person I partnered with four months ago and the one I met a month ago. The four-month partner dislikes the newer member, but when I ask for reasons, he remains silent and simply says he doesn't like him. Despite the one-month partner's efforts to build a relationship, nothing has improved. I've been working on this project for over a year now, and I'm facing a dilemma about what to do next. Please help