I’m also finding work really tough and miserable because of this. Are you in a job where you can wear earplugs or ear phones? i’m looking into plugs that may muffle the offending sounds or earphones that could drown it out entirely but it’s not ideal.
Do you find it gets worse if you find someone dislikeable to start with? I do. If I really like someone but they eat loudly – I find it irritating. If I find someone obnoxious from the outset and they were to make the same noise – I will feel ready to explode and will fixate on my anger at them.
I’m assuming talking to her is a no go. You could mimick pain next time she laughs (exclaim ‘ooouch’ and hold your head. If she asks you what wrong, just explain you have an ear sensitivity issue. People are more likely to be sympathetic if they think something causes you physical pain.
Probably terrible advice!