Can I break a lease if only I have signed it and my fiance hasn't? We haven't taken keys yet.?

I signed my portion of the lease, however, my fiance was out of the country and she'll be back on Tuesday to sign her portion. Unfortunately, our vehicle broke down and I used money that included my first month's rent to fix it. Thus we cannot afford the apt at this time. Lease is 3 days old but we have not taken keys yet until she signs her portion. I gave them a check for the deposit and app fees the day I signed. Can I still break the lease if she hasn't signed her portion and we haven't taken keys yet despite the lease being 3 days old?