If there is somebody you can talk to please do. Even a very trusted friend or family member you can vent to is better than keeping those feelings bottled up. Because it is obvious affecting your schooling negatively.
Now for the tough love part. Skipping lectures and showing up late for clinical can and very likely will cause you to be failed if it continues. The mediocre grades I am not as concerned about as long as you are maintaining a passing grade but be careful to not let them slide much more. School is a relatively short period of time when you look at it in the context of the time you will be putting into your career.
One last reality check for you. Yes, school is hard with high expectations. It should be if you are going to graduate with the minimum skill set required to work as a nurse. The first year or even two of work for a new nurse can be brutal so the stress you are feeling now might not be less when you do graduate, pass the NCLEX and start working. So if you are going to succeed, and you can please talk to somebody to help you through it.