Hey, don't get discouraged yet. To me it sounds like it could be a great opportunity.
Don't think of it as end, but a means to end. Lets say you go for it. Don't look at it as a failure if it doesn't work out. As long as you haven't lost your shirt. That's why careful planning in the begining can pay off in the end.
But it is possible the symbiotic relationship could produce more for both of you than the sum of what each could do alone. I have found that many times with my bro. A job that takes me 2.5 days alone is 1 day with him.
Then there are the less tangible, like the lead that you didn't have time to follow up, that your partner did. Then you get 2 great leads from them. I have countless stories like that.
Sit down with a piece of paper and sketch out specifically what your duties would be, what his would be and how each other would be compensated. Do this more for you own sake...as an exercise to get your thoughts on paper. Then what happens if one puts in more hours than the other? What if one starts to slack under the other? These things are simple when one captian is steering the ship, but with both of you on the wheel you either have to spell it all out for each other or have a real intuition for what the other is thinking. Believe it or not, intution is how my bro & I still do it, but we already have similar DNA, think alike, and know each other vey well. We can work the same project without talking and it is like four hands, almost spooky. I don't expect this to be the case for most.