Illegal immigrants aren't a race so being anti-illegal immigrants isn't racism.
As to whether or not it's true there's evidence on both sides. Here is a good summary:
https://www.factcheck.org/2018/06/is-illegal-immigration-lin...
But you and I are not having the same type of argument that Trump is having. You are taking a reasoned and skeptical position. Trump is not. Trump is not going in front of his rallies and saying, "While the evidence doesn't yet support it, I believe for this and that reason that Mexico is sending rapists and such across the border." As far as Trump is concerned, no research is required. He already somehow knows, and he knows with such certainty that he will happily make unmoderated statements to thousands of people, over and over. To him it is self evident that the Mexican illegal immigrants are largely rapists and assaultive criminals. If he paid attention to the same evidence you do, he would moderate his statements--which he does not.
That fundamental disconnect with factual or consensual reality is why I find Trump abhorrent.
Thus, when Mexico 'sends' people across, they are, indeed, 'sending you', in that the crowd of presumably-legal Americans he's talking to are just as likely to have rapists among them as a group of illegal immigrants. He's playing on peoples' notion that it's self evident that a bunch of brown people crossing the border will be rabid criminals.
Sure, he's willing to downplay his beliefs to the press, but even mainstream Republicans found his retention of Stephen Miller in a primary influencer position to be abhorrent. If you aren't racist, you don't put a racist in charge of immigration.