If I understand correctly, you'd like to talk to your brother about this so that he understands and agrees that what he has done is not okay. And you're afraid that he'll be upset and defensive during this conversation.
Some tips when having this conversation :
- Keep a neutral voice. Don't sound angry, or annoyed. You have every right to be, but if you come of as aggressive in your tone, this will make him defensive real fast.
- Instead of focusing on your brother's behavior and how he screwed up, talk mainly about you (you need the money, you were hurt) and on the possible problems he'll face in the future (people won't be as quick to help him in time of need).
Here's how you could start such a conversation with you brother :
Could we talk for a bit ? I'd like to talk about the 700 dollars I loaned you a year ago. I still haven't received anything back, and the fact that my own brother doesn't pay me back money I need is hurtful. Can we talk about how and when you'll pay me back ? I need that money.
I won't directly mention his vacations and others, because this risks to put him on the defensive. When he responds, probably again saying he'll bring some next time, here's what you can say :
That would be great, but it's not the first time I've heard that. You seem to have enough money to go on vacations and buy a new car, so why is it so hard to pay me back ? You must see how this looks to me. I hope you'll find a way, not just for me, or because it is the decent thing to do, but because people remember. If you ever have money troubles again, people will be a lot less quick to help you if they know you're slow paying them back.
EDIT (from comments) : the tips I provided are IMO your best chance to say what you want to say to your brother while trying to keep the conversation calm. There's a chance that he'll still get upset and defensive, but this is because you're going to bring up a sensitive subject (money), and you want to tell him how wrong he is (no one likes to hear that). I've tried to soften the scripts, but in the end you want to say some harsh truths to your brother.
If he gets upset during your conversation, I suggest to :
- Keep a neutral tone, be calm and kind. People take their cues from you, so even if he gets agitated, if you don't, it should stop things from escalating.
- Hear him out. Ask questions, like if you're mistaken about something (maybe the vacations were paid by his wife or his in-laws). Having a dialogue instead of you lecturing him will probably go over better. Also, since you're mainly in the right, it should force him to acknowledge what you said, which should calm him down a bit (some people it would wind them up more though).
- When he's done, say you understand that this is a difficult subject, it's upsetting to him, and you don't wish to hurt him. But that it was important to you to have that discussion with him because his actions have hurt you, and you know that's not his intention. If you did the same, you'd like him to also tell you.
This isn't a guarantee that he will calm down and listen to you, you can't control other people's reaction (plus, I don't know your brother, this is just general advice that might not be applicable to him). There's also no guarantee your brother will end up agreeing with you. There are no scripts where you can be sure this conversation will go exactly as you want. I gave those tips because from your question, I got the feeling your primary goal was to tell your brother some things, and to avoid upsetting him as much as possible. If your primary goal is to not upset your brother, or the best way to get your money back, I'd have advised differently (namely, don't mention the vacations and the car, focus on the money you need, set a date on when your brother will repay you).
Some extra advice / piece of mind : after this conversation, I would let it go (unless you really really need the money). This doesn't mean forgiving the debt, but just putting it out of your mind. Because if your brother still hasn't paid you back now, he probably won't, and getting angry and frustrated about it won't help you. So after this conversation, just assume you won't get the money back. And if he does pay you back, it will be a delightful surprise. This doesn't mean you have to forget everything : you've now learned something about your brother, keep it in mind.