Help required for approaching a crush after awkward scenario

I'm 25 and have a huge crush on this girl who is 29. We were working in the same office and were casual friends. I guess she also likes me as I noticed her staring me several times. Also, she was the first to initiate the conversation most of the times when we met in the office (I am a bit of shy & introvert type). Also, when once we were passing by each other through the office corridor, I just walked straight without making an eye contact with her because of my nervousness, she followed me couple of steps and asked me why just I passed by without greeting or saying anything. So, because of these reasons I felt there are chances she also likes me. So, once I casually asked her reason for staring, she got tensed and said there is nothing like that and I'm like her younger brother. But I think, she said this in stress because she might have thought I was complaining and I'm younger than her. But I'm not sure about this. Because she asked if there is any gossip of her staring me in the office. She seemed very much worried about that. But there was really nothing like that. I told her. But she did not seemed convinced and I feel she believed about the gossip which never happened. I’m from India and most of the people here are not open minded about such things. They consider the people in love, relationship as spoiled and mock at them. So, because of this, I understand her tension if she believed about the gossip. I think the question about staring have freaked her out. I agree that was a damn stupid approach. I regret that. But I had no intention of hurting her and was expecting a positive response from her on that question. I have said sorry to her if I have hurt her and told her that I was just kidding, and she said it is OK and have forgotten about that. But still she seemed tensed to me. She had left our work place around two months ago (for better job opportunities) only making my chances to approach her difficult as hell. Her memories haunts me every single day since she left. She doesn’t have profile on any social media either. She can be contacted only through phone. I have got her phone number from her friend after she left. But contacting her on phone seems somewhat awkward to me because of the weird scenario happened and the fact that I did not got her phone number directly from her. My dad works as life insurance adviser and sells life insurance policies, so on her last day I asked her whether she has any requirement of life insurance. She said she had not decided about insurance that time. Now I am planning to text her if she has decided anything on insurance. Will this be a right approach? If she says yes to that I will have chance to meet her at least one time on that purpose. But what if, if she says no to that? How do I initiate conversation/message on phone that will not make her awkward if possible? This time I want to keep communication as natural as possible and do want to sound desperate and not scare or hurt her anymore. Any advice on this? How cn i know her true feelings? If she is not having the same feelings as me, I at least want to be friend with her for a long time, for always.

How can you know her true feelings? By believing her when she tells you she's not interested. If she were, you wouldn't need to search for "clues"in everyday interaction. If you believe she's lying, then just ask her out. Don't use insurance or anything else as an excuse to talk to her. Be an adult, and be direct. Just keep in mind that she doesn't owe you reciprocal interest.