Help understand 「せきこみ、喉から込み上げる命の源を思うさまに吐き出す」


I'm stuck in this paragraph :

> 叫び声を上げようと口を開いた瞬間、こぼれ出たのは絶叫ではなく血塊だ。
> せき込み、喉からこみ上げる命の源を思うさまに吐き出す。ごぼごぼと、口の端を血泡が浮かぶほどの吐血。

I don't fully understand the following sentence :

> せきこみ、喉から込み上げる命の源を思うさまに吐き出す。

What I understand is :

> He cough violently, and threw out at the fact he was thinking at the 命の源
> which was making him wanting to throw up.

It might seem like gibberish but I don't want to translate, I just want to
understand

What does 喉からこみ上げる really means ? I understand it as something that makes up
have 吐き気, is it right ?

How to read the 源 ? みなもと ？ げん？

What is the meaning of さまに exactly ? I saw on the dictionary that it means a
"state", but how is it different to "思うことに吐き出す" or something like that ?

Is 吐き出す "vomit" or "say frankly" in this sentence ? I understand it as vomit,
but a japanese friend told me that it mainly meant "思いをぶちまける"..



[code]

    { [ ( 喉からこみ上げる→)命の源 ] を } ( 思うさまに ) 吐き出す。
    
[/code]

  * 喉からこみ上げる命の源 is a noun phrase that functions as the direct object of 吐き出す. 
    * 喉からこみ上げる (lit. "welling up from the throat") is a relative clause that modifies 命の源.
    * 命の源 (lit. "the source of life") in this context metaphorically refers to his blood. This 源 is read みなもと.
  * 思うさまに is an idiomatic adverbial phrase which usually means the same as 思うままに/思う存分 ("at one's disposal", "in abandon", "as much as one wishes"). See [this entry](http://dictionary.goo.ne.jp/jn/33367/meaning/m0u/). In this context, it's closer to 思い切り ("with all one's might"). It modifies 吐き出す.
  * 吐き出す means (physically) "to throw up".



[code]

    { [ ( 喉からこみ上げる→)命の源 ] を } ( 思うさまに ) 吐き出す。
    
[/code]

  * 喉からこみ上げる命の源 is a noun phrase that functions as the direct object of 吐き出す. 
    * 喉からこみ上げる (lit. "welling up from the throat") is a relative clause that modifies 命の源.
    * 命の源 (lit. "the source of life") in this context metaphorically refers to his blood. This 源 is read みなもと.
  * 思うさまに is an idiomatic adverbial phrase which usually means the same as 思うままに/思う存分 ("at one's disposal", "in abandon", "as much as one wishes"). See [this entry](http://dictionary.goo.ne.jp/jn/33367/meaning/m0u/). In this context, it's closer to 思い切り ("with all one's might"). It modifies 吐き出す.
  * 吐き出す means (physically) "to throw up".

