I generally try to be polite over the internet, but here I feel like a stronger tone will be more effective at getting my point across. So, apologies in advance, but here are my thoughts based on how I understand the situation.

You need to give her space or not give her space. You can stay where you are if you want, but to me it doesn't seem like it will get better for either side. So you'll be stuck where you are. Not necessarily a bad thing for you, but it means you're delaying and ultimately prolonging the time it's going to take to finally get over her when you eventually need to. And again, you will need to eventually unless your relationship is much less static than I've interpreted it to be.

Now, as for the depression/suicide bit: I hear you, and I guess you're right that you shouldn't cut her off at the moment, but that needs to change somehow. As in talks with friends/family/professionals. I'm not trying to be a Richard here, but frankly you're enabling her right now. She gets to talk to the nice guy who always says good things and tells her she's right while she hides from her actual problems. Whether it's you or someone else (again, friends/family/professionals) she needs someone to make her deal with whatever her issues are.

And as a parting note, it's up to you to decide how much influence you want to have here, but just doing what you're doing right now without setting the wheels in motion just seems to be doing you both more harm than good.