Did my employer break the law by refusing me to leave work when medical

[curios]

attention was needed? i work as a care assistant last sunday i had an accident at work where i spilt boiling coffee over myself. i eas left with a scald burn on my tummy as large as both my hands. in places its superficial but in places there were massive blisters. i told my employer that i needed to leave as i couldnt stand the pain and his exact response was we cant manage on two staff alone. and that being at home wouldnt make any difference to being at work. he didnt ask to see the burn and didnt help with first aid even though i was in shock said i didnt need medical treatment. anyways after two hours the burn didnt hurt as much and the manager asked to see it it was massive and blistered and he actually told me i did not need medical attention for it. so i managd to complete my shift though clearly in pain. after work i rang the nhs direct and they told me ishould have gone straight to a&e and to go straight away because of the size of the burn. my employer towrds the end of my shift then asked to see it and still did nothing about letting me leave. ive been off sick for the past four days now though because the pain has become unbearable. did my employer do wrong by refusing to let me leave to get treatment just because we are a care facility and need a minnimum staff level?