What's the need for Gauri to expose herself?

Chulbul doesn't want to help Swetlana but Swetlana is blackmailing her to do her work otherwise she will tell Om that Chulbul is working for her.

I agree she could just go to Om and explain everything that happened with Svetlana and he'll probably believe her but the truth needs to come out sooner or later for how long will Gauri hide it? And anyways the longer this Chulbul thing goes the more it would hurt Omkara.

Good point but I think OM's confession at doctor's house shook her so she decided to reveal her real identity.

Yes I agree.She can go straightaway and tell him the truth abt Chulbul.She knows he is trusting her so much.
But her heart is beating for him so hard after he says that he needs to say something to Gauri.She wants to learn it from his mouth so desperately knowing v well that he hates her.

It's better to tell the truth sooner than later. He already invested emotionally in their friendship so if she continues to lie it will be harder for her to tell the truth later on and he will be even more hurt.

Today what happened at doctor's house was big jolt and she wants to end this lie game. It's understandable. She also has lots of pressure on her Om hates her, Svetlana is threatening her to reveal her truth making her do things against Om which she don't want to do. So her decision is good.
But today I realized one more thing that still they both don't know each other much. They kind of know that other person is good and are friends and purity of each other hearts but they have no insight about each others feelings, pains and nature.
Om don't know single thing about Gauri/Chulbul other than his heart's purity as he hasn't seen her life and I have no idea how he is going to react to this truth but Gauri has little insight in his life like his parents fights, Svetlana issue but still there are lots of things she don't know about Om.
She was thinking from her POV that Om will hate chulbul but she doesn't know how it will affect Om. Hating Gauri was easy for him as she was stranger and he just did pity wedding even then he was so affected by her but hating chulbul will be very difficult as he has become a integral part of Om's life. This is good that they showing things slowly and taking time to know each other better.
P.S. Vase sach batana bahut mushkil hai aur use pehle sab log bhagwaan ko yaad to karte hain but bahut log saath-2 vo kaam bhi karte hain jo unka fav. ho as pata nahi baad mein kya ho. So jaise main bahut khaati huin etc to I feel Gauri ka fav. kaam makeup karna hai pura tayyar hokar gayi Om ko sach batane. She looks beautiful even when she removed her wig but she changed clothes or applied makeup or maybe she wanted to meet him in proper clothes of gauri as she don't know will she be able to meet him again.