How do I cancel this date without being really rude?

So there's this guy that likes me a lot, he's fine and nice to talk to but I don't think I'm interested in him romantically and I've recently started talking to someone that I'm pretty interested in. He had asked me over the weekend if I'd like to get food tomorrow (Thursday) and I said that it sounded good to me. But the more I think about it, the less I want to go. I don't want to waste his time or money but I feel horribly rude for deciding now (about 24h before) that I don't really want to go. I'm sure he's a really nice guy. With everything going on in the world as well I just don't feel like going on a date tomorrow. We didn't make official plans yet but I'm sure he'll text me to soon. We met on a dating app btw if it matters, and he normally texts me a few times a day. How do I go about this? I feel really bad. Definitely my fault for waiting so long.