I think this relationship has just been 'coasting' along without any real definition. And that's perfectly fine, until as you've discovered, something goes 'bump'.
No doubt it's been looked on as just primarily about sex, some friendship etc.
If I were you............
I would just get the 3 of you together and lay it on the line. Explain to them both that you consider them both MORE than friends, that you care deeply about them both, and that trauma in their life affects you too - whether they realize it or not. Don't say this in a needy way, but just a straight forward way to make them aware that you do care that much. You can't turn a blind eye to it without feeling guilty.
This is just 'notice'. It's not an obligation on their (or your) part. Just an expression of willingness to help whenever and however you can. An expression of true caring. Isn't that love ?
From there the ball is pretty much in their court. I hope they accept you with open arms but don't get your hopes up either.
Even if not, if you offer IS sincere, you can continue to be on the bench waiting to be called up. It's hard for some people to be that open, and trusting, to allow someone else in that deeply. Sometimes it takes time, small steps.
I hope for you all it works out.