Would leaving him be too cold and selfish of me?

My partner is a freelance creative. He is a hugely talented film maker, director, camera operative. His work truly is stunning and I am not just saying that because I am his Girlfriend. Previously his work has been nationally and internationally recognised. Last year, financially, he did great and saved up a big heap of money. However, 2019 has been rock bottom for him, his work has dried up, he's no longer asked to work on jobs that earnt him so much cash. He has committed to working on his creative ventures- funding these himself on a shoestring budget and still managed to make it look amazing. But this doesn't earn money. His stash of cash has dried up and he tells me he has about 3 months worth of rent left until he is literally broke. We live together, I run my own business which has just started up. The thought of being the provider is quite scary at the moment and I can see us having to move out if he doesn't get work in the new year.
He is depressed, even suicidal at times, the conversations we have are all so negative and revolve around his struggle. I have supported him emotionally for the whole year but now I am at the end of my tether and I'm getting depressed myself because our outlook as a couple is so bleak now. Someone needs to give him a break for his and my sake, otherwise I think I have to go- but is that too cold of me? I am reaching an age where my friends are all married, houses, kids on the way. But I feel like I am stuck in my early 20's with this guy, as much as I love him. Things have just halted to a stand still. I really think he has what it takes to be huge, but for whatever reason, he is not getting a break. I want to stay with him because we are best friends and have an amazing relationship (when he feels brighter) but I don't know where we go from here...
Would leaving him be too cold and selfish of me?
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