going back on offer acceptance..repercussions?

[dapper]

I posted a little while back about accepting an offer from a supervisor from a safety school when I thought all hope was lost for the others I applied to. Well the supervisor didnt give me a very reasonable time frame, said they needed to know my March, and of course I hadnt heard from anywhere by then so I had no choice to accept.

I did get rejected from two of the four I applied to but recently was emailed by a PI at the one school out of them all I thought was a long shot (super pumped!), anyway not that anything is set in stone but of course I will want to go there if there is a possibility

Im worried that if an offer comes I will have to bail on my current PI who Ive already told I would work with, and started summer research and everything!! Will they understand that I really believe its the best option career-wise for me? ORRR will it be a HUGE deal and;

-I lose my summer research job

-they email the PI at the other school who Id be working with and tell them what Ive done...ie, tell them nothing but bad things about me

-Both schools just flat out hate me........and I have nowhere to go

Kind of anxious about this.....ugh

[aberrant]

[contiguous]

I am also in this situation of possibly needing to pull out of a partially-funded offer due to a variety of reasons (but NOT going to another school) and would be very interested in hearing what people say.