There are more than enough people who love cats that are on dating apps. You shouldn’t concern yourself about people like your ex girlfriend who wouldn’t have dated you if she discovered that you had a cat when you both first met.
The beauty of online dating is that the dating app that you choose to use will be filled with all sorts of people. Many will love cats and have cats of their own as pets and others won’t.
You don’t have to worry about those who don’t care for cats. You will have more than enough people that you can romantically connect with on dating apps who love cats. They would most certainly date you if a good connection is made through conversation.