Question:

please no translate websites.

how to write "Sorry if I don't talk to you at school. There's just this thing I have to let go."

Answer:

Gakko de anata ni hanasanakute gomen ne. Tada, nayamigoto ga atte ne...
学校であなたに話さなくてごめんね。ただ、悩み事があってね。。。