Sorry that you are going through this! Keep working hard and don’t get discouraged by getting less than your normal A’s. Give yourself a chance to get adjusted, take advantage of all academic resources, and find 1 club or service activity to get involved in. As others have suggested, study groups are a great way to meet other people.
Don’t worry about your roommate, as long as you can coexist peacefully be grateful and find friends elsewhere.
Please look after your mental health proactively- use a meditation app, make an appointment to see a counselor and exercise regularly. Both DD and DS went through this and it was very hard, in part because they felt so alone, but it is completely normal. One of the most important things they learned is resiliency-do your best and don’t give up, even when your best doesn’t seem good enough.