Thank you for putting forth your question. The most intriguing thing about it is what you haven’t said. There is no mention of your sister-in-law’s interest in you, her life satisfaction with your brother, or any effort at romantic relationships on your part. What you have said seems to have come entirely from your point of view, relating only to your needs, and without reciprocity or validation from her of any kind. There is no mention that “we” are in love, or that there is a joint fascination. The only thing that you’ve identified as the foundation for your feelings is the fact that you used to be friends. Specifically missing in that underpinning is any kind of romantic attraction that is shared.
What you have said is that because of this friendship more than 15 years ago “I was robbed of a wife and robbed of a life.” That doesn’t sound like what happened at all. It may, indeed, be what you feel, but did your brother steal her from you? It doesn’t sound that way. It sounds like you didn’t make your feelings known, and that if you did your sister-in-law didn’t respond. Either way, she has chosen your brother, and it doesn’t sound from your email that she has chosen him over you. While that might be upsetting it doesn’t add up to you being robbed of a wife and a life. In fact, saying that may be the very reason you are not moving forward.
She was never “yours” in any way, shape, or form to begin with. How can you be robbed of something you don’t have? Your brother has won the girl of your dreams and so there is nothing left for you to do but pine over it, be angry, upset, and confused. Staying stuck and wishing things were different—particularly since you are saying that it is only you that is in love with her. Never once in your email do you say “we” are madly in love. This is one-sided. Otherwise, you would be talking about this as a joint complication between the two of you. Instead, you are talking about it as a highly personal internal struggle. You thoughts operate more like a fantasy than a complicated love interest.
Finally, you say that you are not a jealous person. The typical definition of ‘jealous’ is feeling or showing envy because of what someone else has. This is exactly what you are saying. You wish you had the relationship with your sister-in-law that your brother has. This is jealousy.
Pining over unrequited love is classically human and is as old as the species. But from everything you’ve said this feeling of being stuck may not have to do with a fantasy of what you wanted. The reason it doesn’t get better is that you are confronting these feelings in a vacuum. Otherwise, you would be talking about how the two of you are going to figure out your love interest in each other.
There isn’t enough information in your email to offer more than this, except that in most instances my experience has been that yearning for the one that got away is often a way not to invest in other relationships. I don’t know if that is the case here, but I’d recommend individual therapy to start unraveling the knot that has kept you aching for this relationship to happen, particularly when it hasn’t had much else but a friendship beneath it.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral