红宝石正则表达式分裂字符串。但不是如果它的一部分包含在排除列表中

I want to split sentences by a specific char but just if this char isnt used as a part of a word that is contained in an exclusion list. For example I want to split the sentence by a fullstop "." but I just if its not used after "Dr" or "Prof". For example:I want to split sentences by a specific char bu