1). You need to learn how to be more assertive. You can't put this all on Tom given that you said yes to all of his requests.

2). Tom is indeed a user. You're at the point in life where you learn that childhood friends aren't necessarily meant to be lifelong friends. Now that he has a girlfriend, his friends are only needed for venting to or to do favors for him.

I think it's time to let this friendship go. Don't fall into the pattern of constantly bending over backwards because you want to save a childhood friendship. (Been there, done that, finally got off the crazy train!). The truth is that as kids we have tons of time so our friends always seem to come first or be a priority. As we move into adulthood things change. Some people replace their friendships with work, partners, family, etc as they never learn how to make the transition into balancing various aspects of their lives.

It sounds like you're a people pleaser and you're taking on all of the blame for this situation. Next time tom calls, tell him you're busy. You're not a dog walking service, a delivery take out driver, etc! Friendship favors should be more along the lines of "hey can you give me a lift, my car broke down" as you have done. He needs to take care of his own damn dog and pay for a dog sitter when he goes out of town. Simply letting you eat his food isn't fair compensation. And making you pick up his take out food is simply ridiculous!