Letter of Recommendation from a co-worker's?

[Abraham Mathew]

Recently, I had to leave my job on less than amicable terms on accounts of them mostly being sore on me wanting to pursue higher studies. Out of spite, the letter of reference they gave me was very basic and essentially unusable. My SOP relies heavily on my work experience of 1.5 years that i entered right after graduating my bachelors. I believe it affected my applications when i didn't have a letter of reference to back it up (MS in Computer Science in the US require 3 letter of references and i gave all academic LORs). I was rejected all across the board.

I'd like to ask one of my coworkers working in the company , who I'm still in good terms and have worked together with ,to write me a letter of reference. The general consensus I've received from study abroad consultants is that its not advisable. I can't quite get a read on that because I'm not sure they've really had to deal with a situation like mine to adequately comment on it. Adding to that, i don't think the third academic LOR i have is very strong either.

In your opinion.
 Can using a co-worker's letter of reference be detrimental ?
 Would a strong letter of reference from a coworker outweigh a weak academic LOR?