I’ve tolerated it long enough,（but） finally I talked to him. “还是” is a turn in this sentence，maybe you should try understanding it by reading more similar sentences 他尽管笨，这个还是懂的。 He is such a fool but he knows it. 尽管他有病，他还是尽了最大的努力。 He did his best even though he was ill. 尽管我用尽力气，我还是举不起这块石头。 Try as I might, I could not lift the stone. f you still have any problem, please be free to contact me.

I think it has two meanings. 1.or,You like coffee or tea？你喜欢咖啡还是茶？it means a choose. 2.still, I want to help her,but i still rejected her.我想帮助她，但我还是拒绝了她。it means a transition. The "还是"of "我忍了很久，最后还是跟他说了。" is this one. I hope it can help you.

in my opinion,还是 is used to emphasize the resule of select. At first ,you intend to tell him this thing directly(selection A), but you are worried about the effect may not be good after he know it . so you want to keep silence (selection B), you've toleranted a long time , but at last you still made your choice to speak out. you go back to selection A . 还是 here means still remain the same circumstances or go back to the initial situation. hope my answer will help you.

1、“还是” 用于的是选择疑问句，“你去吃饭还是回房间？”“你吃包子还是吃饭？”。所以，“还是”应该用于有选择的句子。 2、“我忍了很久，最后还是跟他说了。”这个句子中的选择是“忍着，不跟他说”，“跟他说”；“在这句陈述句Declarative Sentence中，“还是”后面接的是选择的结果，而且“还是”还表达一种“在考虑了很多东西之后，做出决定”，说明做这个决定是很难的，但做出了这个选择。

I still told him.不知道写的对不对，大概就是still的意思