My Co-Founder Doesn't Want to Commit. Pls Help.

Hi Guys, After almost a year of development and working part-time jobs, we launched our company last month and have gotten tons of great press, investor interest, customer interest, etc. Mashable just ran a story on us this week, a major magazine is coming over next week to do a photo shoot to accompany a story they're writing about us, major media companies have approached us to partner, and top tier angel investors are interested in doing a seed round. All awesome, except for one thing: My co-founder/CTO (50% shareholder with vesting) doesn't want to drop out of grad school and commit to going full-time. Initially, this whole thing was my idea and I convinced him to do it with me because he's a super smart dude who gets shit done and has already helped one startup get to a successful exit. But that was a few years ago. Now he's in Architecture school and living in Europe. I'm here in the US. When I originally contacted him, we hadn't spoken for >5 years and he had just started this architecture program after a career doing film CG (like I said, super smart dude). He was bored with school (not technical enough, he said) and I talked him into building a prototype of our product (I'm not a programmer). Then I went out and pitched to a top-tier VC. He said he loved it and even wrote about it on his blog. At this point, my co-founder and I decided to split the equity 50/50, with half upfront, and the other half vesting over 3 years . In the fall, I went to a job fair and recruited 3 more guys to join the team. Initially, they worked on a trial basis as contractors in exchange for iPhones, but now we're ready to give two of them serious equity (above market rates). Since we launched, I've basically blown off my day job and gone very close to full-time on this, attempting to broker deals and raise money. Our initial capitalization came from $8k I put in (most of it a personal loan from my dad). This week, I quit my job and raised $10k from my brother and a high school friend. Big time angels and seed funds are actively interested and talking to us, but a sticking point is whether my co-founder will come to the US or not (we haven't even brought up the not-full-time issue). For our launch, I flew my co-founder out here from Europe, putting the tab on my own personal credit card. I knew that he wasn't going to really get excited about dropping everything unless he was here talking to customers, investors and feeling the buzz, etc with me. At the same time, my personal credit debt has been ballooning because of how little paid work I've done. Now my co-founder wants to finish the semester of grad school and work remotely from Europe until we know the company is going to succeed. There's still too much risk, he says, to drop everything. I can deal with him staying in Europe, but I'm going fucking insane over the idea that I'm taking money from my own family (not wealthy), letting my personal debt balloon and my co-founder, who owns half the company, isn't even willing to drop what he's currently doing to do this as a full-fledged effort. To be clear, I don't want to fire him. Hell no. He's super creative and smart and he's built our core IP. And he's a great programmer. But the current state of affairs just cannot stand. Suggestions? Thanks. -Extremely Frustrated