Seeking Advice: Torn Between Boyfriend and His Best Friend

6monsth back I started talking to one of my colleague, he is attractive by his nature. Almost everyone likes him. he is intelligent, funny, etc.... In calls he used to tell me about his family, his friends, his thoughts, also about the girl (Aliya) whom he liked a lot for 6years (they belong to same village), but she rejected and told that he is her friend only. He told her that he may get feelings for her if they both remained as friends, so better stop talking. But she insisted that they both need to be friends and continue talking. I felt like may be she needed emotional support that's why she insisted. After coming to Jaipur, Aliya started talking to another man named Jitesh. But my colleague used to feel like a third wheel and started keeping distance. Then also she told that they are just friends and he need not distant himself. She always wanted him to give her the first priority. He also feared that she might get upset if he don't give her 1st priority. They used to talk a lot on phone and share everything. One day he brought her to our bay where we both used to sit and work. that day I really felt like I was a third wheel. I felt very bad.. cried for few days. And decided not to talk to him from then on because I didn't want to cry anymore. But he kept trying to have a talk with me. One day he almost cried because I was ignoring him. I couldn't see him like that and also I felt guilt about my behaviour(my intention was not to hurt him but to save my tears). I couldn't help but starting talking to him. He used to mention to me whenever he used to talk to her. and everytime I used to feel very bad. We started talking a lot after few weeks. Whenever I didn't receive proper response from him I used to become very anxious waiting for his reply and cried a lot. But when he starts talking again I used to feel normal. I never wanted to get into relationships, so everytime I used to tell him directly or indirectly about it. But still he continued to talk to me. One day he called me and said that Aliya is in love with Jitesh. He said being a friend he is very happy for her but after sometime he also said that if you also love someone I will stop talking with you also. I understand that he is little sad that he cannot talk to Aliya as he used to talk before because she is in love with someone else. We continued to talk and kept talking a lot. One day I felt like I am too much emotionally getting connected to him and felt like these long talks need to stop. So I asked him saying that I didn't get clarity. Then he opened up and proposed me. I thought for a day and I felt he is also a good person and said yes to him. Then on he became my world. Then on he started talking little less with other girls. One day Aliya called him saying that Jitesh had an incident where everyone thought he was drowned but he came back safely. She needed emotional support and asked him to come to office. She also said she that one of her colleagues didn't bring lunch and she don't have enough food to give her so she asked my colleague to prepare some food and bring it to office. At first my colleague said no thinking of me but Aliya convinced him emotionally saying that will you leave friends if you get a girlfriend and so he prepared lunch and took it to office. That day when he told me all these I felt devastated, I felt really insecured and cried a lot that is our first fight regarding her. He told me that if you say no I will stop talking to her. She again called and asked my colleague that what was my reaction for all these... he kept silent she guessed what might have happened and told that I understand how she might have felt and will not ask him to bring food to office anytime. Then on fights started increasing between us regarding her. whenever we three had a conversation i felt like thirdwheel and felt he is showing more attention towards her, more care towards her. again a fight. Like that fights started increasing. At first he used to listen to me, but after some days he started saying like my thinking is wrong. I even told him how much I cried but he didn't bothered. I never wanted to break their friendship so I never wanted to ask him to stop talking(even though he gave me that option). I only wanted him to give me my importance but I still feel he shows equal care to both of us. Then how am I different? Later on in our every fight, he started supporting her this gave me more pain. One day he said If I leave her for you, then I may leave you for someone else, that is not my character( this is contrary to what he said previously 'I will stop talking to her if i don't want to'). I cried a lot, I don't have much friends I couldn't share this with anyone.... every moment he is only coming to my thoughts and whenever fights happen due to Aliya, I get disturbed a lot... unable to concentrate on my work... not getting interest to do anything. One day out of anger I said just stop talking to her then his expressions totally changed he became hesistant , he became very sad and said I need sometime and don't know how much( his expression is contrary to what he said 'It doesn't bother me much If I don't talk to Aliya' ). He is that much emotionally connected to her. After 5mins I pinged him saying that I am feeling very guilt about the decision and ask him not to stop talking to her. I understood finally that he still thinks I am wrong and I am tired of fighting. One day when I was very emotional I told him that I will no more bring Aliya topic in our discussion and asked him to do whatever he wants. After this, Whenever Aliya calls him or he call her he used to tell me... sometimes I felt very bad... sometimes I tried to ignore as if it didn't bothered me but didn't start any argument with him. After few days he even stopped telling me if she called him or not also. When he was not telling about Aliya's conversations I thought he understood my feelings and reduced talking with her. but one time accidently my colleague's friend told about the small conversation that my colleague and Aliya had, that's how I came to know that they had a conversation but he didn't tell me. I felt very bad, really very bad... again unable to concentrate on work feel like crying all the time... I can't ask him to stop talking to her because I don't like to do so and also afraid of having negative impression on me in my colleague's mind. at the same time, I feel very very bad whenever they meet or have a call or does something together. I cannot discuss with him about this anymore. what shall i do, this is bothering me a lot and also having effect on my career, peace and life. please suggest. I am ready to correct myself if there is anything wrong from my end. And I can surely say that If i have a boy bestfriend then he would definitely not feel comfortable and will get upset.