Sorry this is really long but typing it is quite therapeutic. I've always been a bit of a loner, introvert, bad at making friends and low self-esteem. A couple of years ago I started work in a new city and made friends with a work colleague (male) who i'd known vaguely for several years but up to this point we'd only met at work social events. At first everything was good and we'd go for the occasional beer and have a laugh. But as we became better friends I started to become attracted to him (he's married) although i never said or did anything. We developed quite a close friendship and I felt flattered that he liked me and trusted me and at the back of my mind I always wondered if he'd make a move and what I'd do if he did.
Last summer (2014) I realised that I was getting jealous of him spending time with other women (he has lots of female friends) and I took it very badly whenever he couldn't socialise with me. I was also going through a stressful time at work and my self-esteem seemed to plummet. Whenever i was with friend and someone else i felt not good enough and became quite sullen and withdrawn and also paranoid that he would stop being my friend and find someone more interesting to hang out with. This led to a whole spiral of negative feelings and by the end of the summer I was crying a lot and having suicidal thoughts. I had a little bit of counseling at the end of the summer and a change of work routine seemed to shake me out of it for a while but by December I was really unhappy again and felt awful about myself. I eventually told friend I had some mental health issues going on because he wanted to know why I was acting weirdly but despite initially offering to be there when I needed support he has never actually followed through with this.
At the beginning of 2015 friend got moved into a different work building and this is when the obsession started i think. I found myself lurking in places where I would see him go home, but where he wouldn't see me, to check if he was spending time with other people. He started to pull away from me, we socialised less, and I became quite angry that he didn't like me as much as I liked him. This led to a spiral of him trying to distance himself whilst I had a go at him for not wanting to go to the pub or meet for coffee. In my head this turned into the idea of him hating me and therefore he was definitely going to dump me for other friends. All the while i still had a crush on him and couldn't understand why he didn't like me.
By the summer our friendship was pretty much in tatters, I think he hates me and try to keep out of his way. Then for a couple of weeks we worked on the same project and and we start to get on again. But my low self-esteem meant that I couldn't just accept him being nice to me and I needed reassurance that he liked me. This led to us having a huge row and friend reaching the end of his tether and really being off with me. At the same time he made a lovely new friend who he started to spend time. I became convinced that he was going to start an affair with her and started to 'spy' on them, again hanging round in places where I could see them but where they wouldn't see me. I also started to apologise profusely to friend for my argumentative and possessiveness and tried hopelessly to get the friendship back to where it had been when we first became friends. This didn't work and i watched him become closer and closer friends with this other colleague whilst constantly pushing me away. Yesterday I realised that my obsession was completely out of control because I knew they were going out in the evening and I actually walked round all the local bars in town to see if I could 'accidentally' run into them 9which i didn't). I even contemplated hanging round outside her house to see if he would drop her home. Luckily I managed to stop myself from doing this.
I obviously feel out of control and pretty shit about myself. i think my weird behaviour has been noticed by other work colleagues, which also makes me feel even worse about myself. I want to press some big reset button which will make things normal but clearly this is impossible. i need to stop the obsession because I'm scared I might do something that is actually illegal. I had more counselling for about 3 months after easter but I could never bring myself to discuss the friend obsession, it seemed so embarrasing, so we tackled lots of other things about how i felt about myself but not what is probably the root cause of the problem. I don't know what to do next!