Back to square one

So, I'm finally admitting defeat: the bike I bought used for $60 is too big for me. I don't know how the lady I bought it from rode it, but I cannot and I'm not going to risk cracking my head on my neighbor's split rail fence or on our garage door trying. So now, I'm sort of back to square one, I've found a nice Raleigh 7 speed that fits me perfectly and I can trade in the bike I have now for a credit toward my new bike. Still I'm frustrated that I convinced myself to buy the bike when my instincts were telling me 'that's too big'.