我觉得这个问题很难说清，呵呵，有时界限不是那么清楚的，尤其是这么和那么，看说话者的用语习惯。不过看了上面的回答，我也觉得挺有帮助的。

hi, 伊丽沙白： I am not recreation at here. Just a little bit about this. 那么，多么和这么 you can use that word well. 那么=then ；多么= how, what；这么=like this, such as...

建议你查网页版的新华字典. 这里很多人回答前都不看下字典的. 我是没有听过有人说"我那么孤独""她那么漂亮"之类的. 而且听起来很别扭. 这时请用"这么"..... http://xh.5156edu.com/ 在线新华字典

如此just like so。u r so pretty，and so lovely ，oh Cinderella my only sweetheart。你如此美丽, 而且你可爱至极，哎呀灰姑娘,我的灰姑娘 。《灰姑娘》by 郑钧 多么： how high i am ！/i was fucking high。 多么爽啊。我太他妈爽了。 这么 for the thing near or reality 。 i paid 1 million for this diamond 。我花了这么多钱买的钻石，（100万），是不会轻易交给你的。 那么for the thing far or imagination。 freedommmmmm！when William Wallace shout it out loudly befor to execute ，i was moved deeply 。 i say in this moment，这个灵魂是那么的伟大那么的丰满那么的震撼你我的心灵。 above are as adv. and 那么 can be used as prep. just like then 、 whell、 so ：here come the bus ，那么，lets go。

Hello :) 那么 means a few things depending on where you use it; (那麼)， 我們出們吧 (in this case it means "and so", or "then", or "in which case" lets go out.) 這個句子沒(那麼)清楚 (in this case it means "that" and it's useful to think of it in this sense- "this sentence is not THAT clear" So when you're saying 那么孤独 it means "I'm THAT lonely", as if to say "I'm am so lonely, THAT's how lonely I am". 这么 is a little different. 这么 means this, but it can also be put into the same kind of context as the sentence above (这么孤独) means "I am THIS lonely", and as you can imagine, it's the same kind of idea. 如此 I've not heard many times before, I would say it means "so" (I am SO lonely) 多么 I've never heard before, and I dont know how to use it ;) Hope this is useful :)