I'm going to ask a someone at their lowest to finish paying their rent share
That's concerning. Have you asked to pay their share before?
Yes, he does not pay his share for quite long time.
It is hard to ask somebody who is depressed for money but you shouldn't have to incur their debt. They need to pay even if they are not feeling it. It wouldn't be fair to you and then you will be resentful.
I'm not going to be resentful, it's not my fault that he's depressed. I have tried to ask nicely.
Then you have done what's needed to be done and as you have said, he hasn't paid for a long time and if your rent is really due and he can't pay, then I think it's time to kick him out of the apartment. Depression is not something to dismiss, but you're being harmed by him not paying and it's not okay for you to incur debt in the process.