You are doing a fabulous job. Do not let anyone tell you otherwise.
I have 2 dcs. Dd was a dream baby. Sleeping through at 4 months. Going 3/4 hours between feeds before that. Ds was like your baby. Exactly the same. And at 5 months I felt exactly the same as you.
Excluded from real life. Lonely and exhausted. Resentful of this tiny person who had the power to decide whwhether I slept or not. My relationship also suffered. Everything suffered.
What made life slightly easier was a sling. He would sleep in that for a couple of hours each afternoon. I obviously couldn't sleep myself but I could potter around the house and so stuff for a couple of hours. Make a sandwich. Put some washing in. Get tea ready and stuff. It broke the cycle of trying to get him to sleep. Then feeling stressed when he didn't.
I also got my dp to step in and do something with the baby for a few hours on weekends. Just a long walk or the supermarket shop. And one weekend day I had a lie in. So I would boob him when he woke and dp would bring him downstairs so I could sleep.
I also started weaning with purees about 5 months. Controversial I know but there were certain allergens I wanted to introduce by 6 months.
I co slept when necessary too. Can you feed lying down? Have a google of safe co Sleeping and see if it could work for you.
Now ds is 14 months. Still bf. Still parented by listening to what he tells me he needs. We have just this week moved to self settling. No sleep training required. He goes down wide awake after the bedtime song from cbeebies. I sit with him while he spins around his cot for a few minutes then leave him to it.
He still wakes a couple of times in the night. I boob him. He goes back. 5 minutes tops.
it will get easier I promise. And with some extra sleep you will too. Do you get out of the house much? Baby group is brilliant for a change of scene. As is a mooch around the shops. Visit people. Don't wait for them to come to you.
But mostly remember that this will get easier. Gradually and slowly. Speak to your dp. Get a sling. Go easy on yourself.