Sorry to bust your bubble on this – but to be in love with two men is to be in love with neither. While it looks like a tug of war between the two, it is likely to be more of a struggle you are having with intimacy.
Look at the glowing terms with which you describe your old friend. Perfect; loves you beyond words; you’d do anything for each other; best friend; safe. Now look at the words to describe the other guy: Crash and burn; when you can; fighting; guilty; no good for me. Man. Not even close. If the first guy was so perfect why would there be room for the second so-so one? If the first one is really everything you said, then how could you “fall in love” with the second? When people are truly in love it is like an inoculation against outside interference.
My best guess is that the old friend stirred you very deeply, perhaps very real feelings of intimacy that upset you. The second man is a spoiler – used to sabotage the feelings for your old friend. I don’t think the question is: “How can you love two men?” Rather: “Why did the relationship with my old friend cause me to want to sabotage it?”