Grocery store "meet cute" turned creepy

So I (20F) was at the grocery store after the gym and there was a guy(25M) over there who started talking to me, he did seem cute but then I asked his age and he's like 5 years older than me which is a dealbreaker for me. Still I exchanged numbers with him (this is what I shouldn't have done). He started texting me and asking to hang out, I told him that I'm really busy. Also I had indicated that I can't lead him on since I'm seeing someone( I had to lie about seeing someone since it's the only excuse I could come up with) and he's too old for me anyways. He responded with things like "age is just s number" and "life is all about changes" which just weirded me out. As of now, I've been ignoring his texts and he's still texting me which I find to be quite creepy or just desperate of him. He also told me that he'll be joining the same gym as me (since it's the only decent gym the neighborhood).

How do I get out of this ?