Jasleen and Sukhwinder are still friends and they continue to be amazing friends while they also do concerts together. Also, Sukhwinder and Anup are good friends as Jasleen posted a picture with the three of them in one of her Instagram pictures.
Even Anup Ji has got married 3 times, but are people judging him for that, the answer is no, then why can't Jasleen have past relationships and after breaking up with him, she started dating Anup.
Jasleen has obviously told Anup about it and she just told hm to be quiet because she does not want to involve Sukhwinder in this mess and the audience will start linking her name with him which is happening now, she is a private person who does not really discuss about her personal life., It is completely normal for her to be cautious because people will start being JUDGMENTAL without knowing the entire story.
Jasleen has never hidden anything from Anup otherwise Anup would have never said Sukhwinder's name, she has kept him aware and shares everything about her life be it her past relationships.