if you just want to say you are confused, you should say: something or someone confuses me. in chinese, it is : something or someone 把我 搞/弄 糊涂了。

Like in English, there are many ways to express the idea of being confused in Chinese, each with a subtle difference in its meaning. The most common way of saying "I'm confused" may well be to say "我乱了" or "我被搞乱了". Literally, 乱 means chaos or disorder, which is a pretty apt description of the state of being confused. It also avoids specifying which type of confusion the speaker is experiencing, which I'll now explain. Some of the subtle shades of meaning can be seen by examining the characters involved. For example, the difference between 迷惑 and 困惑 is in the first character of each compound. 迷 is usually used to denote disorientation and temptation, while 困 is used to express the idea of being trapped. Thus, "我迷惑了" indicates being confused by moral temptation and thus being unable to distinguish between right or wrong, while "我困惑了" would indicate being confused because one is confronted with a difficult problem. "我糊涂了" has the connotation that the speaker may be going senile or, more generally speaking, becoming dumb, because 糊涂 means being fuzzy or confused about things in general. As for sentence construction, it's usually the case that you don't use a plain structure, unless you wish to be poetic. Instead, you add a verb, like 搞 (literally, "to do/make", but with the connotation of stirring things up for good or evil), 感到 (to feel) or 被 (only for the case of 迷惑/困惑, which then transforms the sentence into the passive voice). Notice that I left out 搞混了 in your third sentence. This is because in this sentence, "confuse" is used in the sense of "to get mixed up", i.e. "Don't mix up Johnson and Jonson". In the Chinese sentence, 混 means "to mix", so 搞混了 means to make something become mixed up.