Timing Belt broke

I was driving at work about a week ago, and parked it in the parking lot and went inside to close the store down. After about a 3-4 hour wait it wouldn't start back up, or turn over. Eventually I got it towed to a shop and replaced the timing belt, serpentine belt, water pump etc but when they were finished they said that it was running rough and had white smoke coming out the back of the exhaust. I'm not sure if this would be a valve issue, gaskets, or anything else and was looking at whether it would be worth fixing it or buying a used car to get me through until I could save up enough to get these repairs done. I drove it 5 minutes or so back to work to leave it there, the engine really vibrates and rattles as you accelerate and especially when you have to stop at a stop sign or a red light.