I sympathize. I remember the day I turned lonely. I was nine.
It hasn't really gone away since, though it waxes and wanes. Even if it's still present, I have learned to cope with it better. Simply accepting it for what it is helped to ease the suffering associated with it. Which I suppose is to say, I (mostly) stopped grasping for people and things to ease my loneliness, and just went about my life. As a result, these days the loneliness, though still there, is more of a gentle background hum. Sometimes it spikes, but if you don't cling to and indulge in the emotion, it passes. I have also come to learn that being around people makes me lonelier, so with this knowledge in mind, I can sort of brace myself before going out socially, or, if I'm already feeling lonely, I can refrain from going out and worsening the situation. I have also found that connecting with people here can help.
I'm sorry to hear that you're suffering. I don't know if my words have been encouraging or helpful in any way, but I hope that you can find some solace here.
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"A flower falls, even though we love it; and a weed grows, even though we do not love it."