I wouldn't go as far as to say INFJs have a harder time with heartbreak (perhaps they encounter heartbreak more often than some for various reasons, but I don't know how anyone could prove such a thing). Heartbreak is heartbreak. Pain is pain. People express and deal with it differently, but the intensity of it probably has more to do with the situation more than personality type. People feel connected to each other in different ways, and therefore feel broken in different ways when that connection is severed or recognized as one-sided. It is easy for some people to separate the physical from the emotional. He walked away easily because he likely didn't feel the connection that you did. That hurts you, I understand. However, it also means that you were not a good match, and when you like someone and feel connected to them, this is not an easy thing to accept.
Analogy time: You know how when playing a computer/video game the first few levels are so easy, and you feel all good about yourself? But then you end up getting stuck on a harder level, and no matter what you do, it seems like you just really can't get past it. You probably get a little frustrated and lose confidence in your abilities. Now, if you're stubborn like me you keep trying until you finally beat the level (or realize you don't actually care about the game and move on). Maybe you take a break for awhile then come back to it with a clearer head. Or maybe you start coming up with different strategies. Either way you do what it takes and you make it. After that, your sense of accomplishment is even better than when you beat the easier levels since you know you overcame a difficult obstacle.
Sometimes, in life, you probably feel like you're stuck on that hard level. Been there, done that (...am there, doing that). There is no cure-all for heartbreak or suffering in general. You do what you need to do to get through it. Know that when you do get through it, because you
will get through it, you can allow yourself to feel that greater sense of accomplishment. Life, as you well know, is not easy, but there is a lot of good in it. It's harder to see the good when your emotions are clouding your mind/thoughts with all the bad. Be proud of yourself for all the victories. Even little things like smiling at a stranger, getting out of bed (because we all know that some days this is indeed a victory), appreciating a sunrise/sunset, those moments when you do things you don't really feel like doing but know are good for you, etc. You can't make heartache go away in a day, but you can try doing something everyday to help. Look for a fresh/better perspective, talk to/be with friends, and recognize that hope is always there. Think about times in the past when you've felt similarly- when you thought you didn't know how you could possibly get beyond this...but then you did.
Hang in there.
