Crying is okay. Being emotional is okay. Feeling lonely can be really hard.
I wonder if you feel it extra hard due to putting a lot of negative value into being lonely or emotional. Like, do you equate being alone with being a bad person or having failed in some way? A lot of us do. Try to untangle this and not consider loneliness a flaw. It's just a condition, like being cold or warm. It can be uncomfortable, that's it.
I feel lonely sometimes. When I do I read books, particularly fiction. In doing so I get to experience the characters lives and feelings and struggles, and I feel less alone. Riding my bike to the library and perusing my favourite sections or even staying for a read feels like I've done something worthwhile that day.
I have joined book clubs to discuss certain books, and come to appreciate literature where most of it went over my head before. There are clubs online and in person. I prefer in-person because I find it difficult to speak up on mic. Libraries are awesome. As are book/game/culture shops that may arrange themed clubs or events.
Some people with ADHD have trouble reading, audio books are a perfectly valid option. Or any other hobby or activity.
Being in nature is always good for mental health, as is animals. When I had time I volunteered at pet shelters. It feels good to do good. If you have an acquaintance with dogs you can ask if you may join them for a walk or hike next time/next weekend. It will give you a chance to go out and be in nature and spend time with another human. Even if you have nothing to talk about just walking and focusing on a dog and pointing out a strange flower or cool colour is enough. Being in silence in nature is healing. Wear good clothes.