Do not go gentle into that good night.
Rage, rage against the dying of the light.
There may yet be a circle of friends who can be the friends you need when optimism isn't enough.
There may be a soulmate who loves you enough for who you want to be that they will invest their own time and energy in understanding you and gradually shifting the balance between highs and lows.
Opening up to doctors, therapists and peer groups is hard because of the difficulty in understanding their motivations and the fear that you're creating your own future painful experiences.
People change; their needs change; your needs change; The best support is that which helps you need less support. Trees which are tethered to their stakes too long can become girdled; that which supported them as they grew becomes a noose that destroys the flow of water and food. It is possible that your ability to empathise and examine has helped your former friends grow and develop new lives, whilst examining your own situation, thoughts and feelings is just picking at a scab that's never been allowed to heal.
However you change your perspective will always have the same character. A tree will only ever see the shadow under its leaves, the scars in its bark, the dirt beneath it where little will grow from the meagre light, moisture and nutrients that remain.
Your view of others will look brighter and more perfect than your self-image.
The more valuable friends will open up to you, show you that behind the positive image they have the same scars and past trials that you bear; they will remind you that these carry no shame but the events that caused them are experiences which will support them.
Those who have no scars are they who cannot know what will hurt them; don't allow them to lead you to the pain you've felt before that they won't understand.