私と元彼女達と比べないでって英語でなんて言うの？

"Please do not compare me to your exes." This politely tells him he must not compare you to his past girlfriends.

"Please don't compare me to your past girlfriends." This is also another way of saying he should not compare you to girlfriends he has had in the past.

"I do not like it when you compare me to your ex-girlfriends" This explains to him that you do not like it when he compares you to old girlfriends he has had.

If you want to be specific, you can ask someone to not compare you to their past relationships by asking them to not compare you to their previous girlfriend or boyfriend. We can also ask them in a more general way to not compare us to anyone else.

*I don't like it when you compare me to your exes.
This means that you do not enjoy it when they start comparing you to their exes. Maybe your significant other is doing it without realizing that it affects you and talking about it will help the relationship.

I'd rather you not compare me to your ex girlfriends, it makes me uncomfortable.
This statement is polite and it expresses your desire to not be compared to your partner's
exes.
Telling him that it makes you uncomfortable will make him understand how you feel when he does it.

Explanation: Well, making comparisons between you and previous lovers is not the kindest or most gallant thing a man can do! Every ex marks the complete failure of a relationship and a short reminder of that point may better focus this person's efforts!
Example sentence:
"I could make a few interesting comparisons between you and my ex lovers too!"

Use please as it shows that you are being gentle. Using the words 'cared about' instead of 'exes' or 'ex-girlfriend/boyfriend' shows a level of respect for his previous love life that occurred before you met each other.