In animes only, I have heard repeating words like 俺は. For example: 「俺は、俺は」. Question is, what does this try to achieve? If memory serve me right, I recall it only being used by someone in a very bad state of mind. For example: 死んだら、俺は俺は, and the sentence never complete. Literal translation gives "if you die, I, I", which in english at least doesn't makes sense. So what does that sentence mean in japanese?
It's merely an incomplete sentence. It's indeed "If [I/you] die, I, I, ..." and nothing more. Maybe you missed the the remaining part of this sentence in the next page. Or maybe he was simply too upset or weak to finish this sentence. Or maybe he wanted to continue this sentence but was interrupted by another character. Usually something like 悲しいよ, 困るぞ or どうしたらいいか分からない would follow, but it entirely depends on the context.