I think few months down the line you would feel stupid yourself for not having got him as a cofounder. Launch it together, aim for a higher value such that your 50% means more than the 100% you would own otherwise.
Yeah, you (OP) are probably stupid to try to do it on your own if you have a capable cofounder readily available. I'm on my own, and if I knew someone who was interested and whose skills and character I could trust, I'd jump at the chance to bring him/her on.
