Saying goodbye to someone who had touched your heart is not always that easy.
However, should you've to do it for whatever reason(s), then do it with good intention. Never say goodbye with anger or hatred.
If possible, find a way to write or say something fondly to reflect your emotion and character. As an example, "It is certainly an honour and a privilege of having known you".
From there on, you can start writing the next chapter of your life. More often than not, some of the things are better left unsaid.
Be brave to remind yourself that it is all right or O.K. not to be perfect.
You think that you should never have cared, but thanks to ALLAH that you did care. Even Nabi Muhammad SAW cares for us (his followers).
In whatever things we do, we should adhere to the principle of worrying less about what others think, say and do.
There's a saying that goes:
27 Rejab (Israk dan Mikraj) 1437H