So I cut and I want to stop. So I started to smoke and I have become not as depressed and stuff. Is that good or something? I really don't know

It is called replacement.

It is also called self treatment.

I smoke,have been for @30 years,I can't say don't do something that I do, I don't cut,never have.

You are replacing cutting with a different outlet,that in itself isn't terribly wrong,What I would ask is,eventually,smoking will be needed to be replaced with something else,maybe something healthy, walking,jogging,tennis,woodworking,cooking, replacements can be temporary or permanent,they can be for the good,like cooking/etc,or for the not so good,smoking,

How long you chose to continue is entirely up to you, problem is you need to find the reason you cut in the first place,smoking is only a mask with which you are covering the same issue that cutting was needed for.

Make sense?

OK, smoking is a lot better than cutting since the danger to you is less and it is much more socially acceptable.

So if it is a choice, of course smoking

But you are not addressing the issues and the problems that is causing this, which needs to be done.