While I think the three of you have great potential for a successful, loving triad, I also see great risk to you, of becoming grossly co-dependant on these people. That is not fair to them or to you, and it is not loving. If you really want to have a healthy relationship with them, you owe it to them and to yourself to deal with your depression and get ahold of this desperate neediness you seem to be experiencing. No one (or two!) can fill that for you, and it will only lead to frustration for everyone. Do not look to this 3-way relationship to solve all your problems! I have been extremely lonely too but I know if I depend on someone else to rescue me from that, I am going to be "too much" for them. Make some more new friends! Let these lovers be the proof you need, that you ARE lovable, and put yourself out there again, for friendships. I think the more you broaden your social circle, the more special this triad will be for you. And -- the less fearful you will be of it ending.
Ugh, I hate to sound negative, when I really see a lot of good potential for you 3! But as a recovering co-dependant myself, I felt I had to speak up. Best wishes, and welcome to the forum.