Help! I need to back out of a sales contract.

[Hanan K.]

An agent approached me about a client who is interested in my primary residence. There is a home a few doors down that just went on the market for 999K.  I hired an agent to represent me in the sale of my home and asked that she proceed with all correspondence with buyers agent  I explained to her that I would not agree to any purchase until I know what the comp down the street is under contract fo. The reason for this is that we live in a very unique neighborhood with restored mid century modern flat roof homes. Our street is tree lined and stands out from most streets in the area.

the agent presented an offer to me and I explained that I would not accept an offer until we knew what the comp was on the house down the street. She then proceeded to tell me that it was under contract for 1,050,000. She said she received that Information from the listing agent. 

I used this Critical Information to make our decision and we accepted an offer at 900K since the other house had a lot more upgrades. 

Come to find out the information she provided was completely false and it actually closed for 1,130,000. 

I now feel that she was negligent with the comp she provided and my entire decision making process was based on this. 

What can I do? I want to cancel the contract. I now know I am selling for severely under market value as even though the other home has more upgrades, mine is much larger, same style and completely updated. 

Is there any way out based on my agents negligence?