Riding that bike is stupid. I would like to be more polite about it, but I feel the need to be blunt.

The smart thing to do is retire this bike for now, buy a garage sale beater for ~$25 and fix the mountain bike (replace the frame with a decent rigid one, get a good suspension seatpost when you can) when you get a chance. You can get a bike at a garage sale for around the same price as buying the materials necessary for your bad-idea-repair job.

I am familiar with those entry-level specialized full suspension bikes, and while I have not seen too many of them fail, the frames aren't so great that they are worth saving if they do.