How do I tell someone I like them without ruining the friendship?

Say it simply and without pressure, for example that you have noticed your feelings and wanted to be honest. Make clear they do not owe you an answer right away. Be ready to accept a no and to give the friendship some space. Honesty said kindly rarely ruins a good friendship.

Tell them how the lack of apology feels, with a recent example, and what you need, such as "I would like you to acknowledge when something hurt me". Model it yourself by apologising sincerely. If it never changes, think about whether this pattern is acceptable to you.