I've not been participating much for a few months, so perhaps we've gone back to the touchy, feely EMT City, but I didn't really see any significant issue with mfprincess' post.
The OP, who I applaud for having the courage to search for answers as well as post an experience that she's not very proud of. To say that she is not emotionally equipped to deal with these kind of situations seem self evident to me. The cknowledge that she is not currently equipped certainly doesn't imply that she's to weak, or stupid to become equipped, in fact instructions for doing so followed the comment. Perhaps msprincess pissed someone off in other threads...don't know. The OP presented her story clearly, and honestly, I didn't get the feeling that she came here to be coddled, but to become educated with a decent dose of empathy thrown in to boot.
But the fact is, you are not currently emotionally equipped to deal with such a situation. Non of us was the first time we saw an emergency, but you can become equipped. What worries me more than the emotional aspect of your response, as you will react completely differently next time, is the fact that you state that you've taken a CPR class times three yet don't seem to understand that a breathing person does not require compressions (in the BLS environment.) If you were confident that he was breathing there was nothing medically that you could do for this guy. Physically you certainly could have as explained before, but even then, unless you allowed him to flop off of a balcony or some such thing, you shouldn't feel responsible for his condition or the outcome.
I found my grandmother dead in her bed when I was 16, long before becoming involved in EMS. I couldn't touch her. I said, very quietly a few times as if speaking aloud might bring out the ghosts, "Gram, are you ok?" and then went and called 911. Did I act that way because I'm some idiotic emotionally unstable pussy? Idiotic, often, emotionally immature perhaps but not unstable, and I doubt anyone that knows me would define me as a pussy. I simply had no tools for that situation. My brain tried to lock into my past experience for finding dead people, found nothing in the toolbox, so I acted silly, random, and called for help. There is no need to be ashamed of that, and I'm not.
I mentioned that I was worried that you didn't seem to understand that a breathing person doesn't need compression, but I'll tell you what wipes that worry clean off of the plate for me. The fact that you were brave enough to tell your story and actively seek constructive criticism and advice. That is friggin' awesome! Cast iron reproductive organs are often necessary in these situations, and you seem to have that in spades.
Retake your CPR class, perhaps see if there is the possibility to ride along with a local ambulance, stop using the language "I didn't want to kill him." as that is mentally damaging as well as being completely inaccurate. You didn't put him in this situation, (Or if you did, ignore the rest of this post and go and turn yourself into the police.) you couldn't have prevented it from happening, it was not of your doing. You have to eliminate that "stinking thinking" that says, "If I help him, and he dies, then I killed him." If that is the case then I've killed dozens of people. Do you see?
I am going to criticize your inability to afford an AED. You have chosen a profession that puts you in regular contact with high risk patients. You've chosen to try and help them physically, yet have also chosen to allow them to die needlessly while in your care by not preparing to save them. In a new business I can almost guarantee that you have spent more on carpeting, curtains, electronic equipment individually than the cost of an AED, yet you've found those things more valuable to your patients than a simple, proved, life saving tool. That doesn't seem responsible to me.
Most importantly? YOU WILL NOT ACT THE SAME WAY IN THE NEXT EMERGENCY. I guarantee it. Your toolbox was empty last time, you had no experience to draw from. That is no longer the case. Do you want to add more tools? Absolutely, in fact you may find that you want to install some mental pegboard to keep expanding once your toolbox is full, but you have a significant advantage next time you're exposed to this situation that you didn't have last time. Also you'll take your next CPR class in a completely different context. Things will stick now, where they didn't before.
Cut yourself a bit of slack. You were a victim at this emergency, yet you have the ability to prepare not to be victimized next time.
Good luck.
Dwayne