My toddler wants to fondle my breast every night before bed

My son is 2 years and 7 months old. He breastfed until 2 years and a month old. He had a really hard time stopping, and cried nightly due to wanting to nurse. He always went to sleep happy but he would ask me if he could nurse and I’d say no then he would be sad.

One day I said okay baby how about you just hold them? I was thinking it would help him adjust to nursing for comfort to nothing at all. Well it’s months later and I can’t get him to stop. He says “mama can I hold your boobies?”. He will then hold one, and he will kinda use his thumb to touch my nipple. Or he will kinda twist my nipple. Sometimes he will reach up and kiss it. I don’t want to sexualize this. It doesn’t seem sexual to me. But it needs to stop. Is this normal?

Am I awful for letting him do it?

How can I get him to stop?