Respecting his opinion does not mean that you do whatever he says. It means that you have considered the options and his viewpoint, weighed the pros and cons for you, and decided to go with what you feel is right for you.

And if he attempts to convince you that "respecting his opinions," means doing exactly what he says at all times even if it is your body and your illness, well, you shouldn't be with that person.

I am severely mentally ill and my boyfriend is generally against psychiatric medication and prefers to treat things naturally, but he doesn't give me a hard time about it because this is what I've decided is best for me (and really, there's no other option). If you had diabetes or something I'm sure he wouldn't be giving you a hard time. He's just internalized the stigma surrounding mental illness in general and it's okay for you to tell him to butt out.

He sounds like a jerk in general btw. I hope your depression isn't keeping you from moving on from a bad situation.

Also, are you in therapy?