1) Abruptly 2) Cruelly 3) Nastily 4) Pitilessly 5) Unfeelingly 6) Unkindly 7) Unsympathetically 1) Coldly 2) Distantly 3) Frigidly 4) Frostily 5) Grimly 6) Hard-heartedly 7) Impersonally 8) In a callous way 9) Insensitively 10) Pitilessly 11) Stonily 12) Uncaringly 13) Unemotionally 14) Unfeelingly 15) Unsympathetically 
[adv] - in a callous way
adverb in a callous way; `he callously exploited their feelings`