Firstly I want to congratulate you on your resolve.
Yours is twice the weight (90 kg x 2) of a normal heavy rider. I see that bike you mentioned is a very cheap bike. For your safety DON'T!!!!.
I can recommend that you do a LOT of searching online about bikes for heavy people, find examples that have worked for people at or above your specific size and weight.
Here is one very interesting blog by someone who lost weight and "reclaimed" health through bicycle riding:
He recommends a 29er with fat slick tires for road use. It sounds good. You will notice he mentions $5000 to $6000 dollars as a price tag but I think it doesn't need to be that much.
"Surley" (http://surlybikes.com/) is a US company that makes sturdy steel bikes at a reasonable price. (I am planning to get a Surley for my next bike). They have contact information on their web page.
I hope they are as friendly as their website looks, and they would give you the info about what bike would suit your needs. Then you could go to a LBS which is a Surely dealer to get the bike you want and have already confirmed would suit you, who could also help get the details right like the right kind of saddle. I guess you could do it with budget of $2000 US.
I'm 80 kg and I have a scar above my left eye that tells me that "cheapest" does not make sense when choosing a bike. Even more so for you.
Good luck dude!