It's her defense mechanism, she might not admit it not even to herself that she loves him or cares, but her reaction itself whenever Neil or love are mentioned shows clearly that yes farak padta hai. If u notice, she is calm in all other situations even when she thinks about Vidyut, but with Neil, she feels sadness, hurt, disappointment and anger because he didn't trust her (that's what she thinks) and broke his relationship with her (we know it's not true, mangalsutra is different and he wiped the sindoor he applied while she had another sindoor the one she applied before) and more because during all these 6months he didn't come one single time to see her or ask about her and now she sees in TV that he is enjoying his job and is even appreciated for it without thinking about her.
Avni has always been like this with Neil whenever she felt she isn't trusted or loved by him, remember the Gazebo time, she was angry, remember when Ali was kidnapped and she thought Neil didn't believe her and didn't trust her, and then when Neil accused her of taking Juhi out, she uses harsh and very hurtful words when she herself is hurt badly by him but all these are just reflecting how much she loves him and how much he impacts her, I feel that her aim is not only to destroy Vidyut but also to prove her innocence to Neil because that's what mattered to her the most.
Due to her self respect and her ego to some point (positive wala ego), she will never admit that she still loves him or cares about him, not even to herself but deep down she loves him but she is so hurt, and I'm sure when she will meet him she will be cold to him (facade/pretense, her heart will be affected) and will say some of the most hurtful things ever but as I said all these things only show how much she loves him and was hurt by him.