So lets pretend I am a tech lead at a AcmeCo, I quit and start a startup, and an old teammate wants me to hire him. But he is an important employee at AcmeCo an

So lets pretend I am a tech lead at a AcmeCo, I quit and start a startup, and an old teammate wants me to hire him. But he is an important employee at AcmeCo and my old CTO will be unable to replace him & his knowledge. I care about my relationship with AcmeCo & the CTO in particular, he is a potential client, we share ownership of some open source offerings, he still mentors me. How could I possibly take any action that damages this relationship?