I had concerns the upkeep of my vehicle too. At some point, I'd need a service that would have bought me a pretty nice commuter. So, the decision was easy. And the road rage bit - it's so odd. I found that very, very stressful. Although I can see the advantage of having a car with the windows up around my scrawny body while some older guy is off the rails because I didn't move fast enough for him. That keeps me off the roads as much as possible.
But the exercise is certainly a plus. I have a rather severe anxiety disorder and exercise has helped immensely. There is quite a bit of evidence that exercise helps the mood as much as it benefits the body. Someone noted once the happiest they saw me was a two year period that was in college. I had no car or drivers license, and had a summer job as a bicycle mechanic that I did part time during school. I rode to work every day, was involved in local races, belonged to the shop mountain bike club, and my bicycle was my primary form of transportation. I don't think that was a coincidence.
I don't know how old you are now, but with patience and a little tenacity, you should eventually be able to do most of what you did in college. As I get older I don't go as fast but I do go further!
It sounds like you might be having some self-confidence issues with riding in traffic. This can be overwhelming, but it can be overcome. One idea is to look into books and classes to develop skills and a good attitude about cycling on the street. A local bike shop or bike club might be able to make suggestions. People here on the forum might have some ideas also.
It sounds like you have a good attitude and I predict that you'll do just fine!
