I'm under so much pressure, I feel like I'm going to explode. How do I keep a healthy mental health?

Emotional upheaval. Feelings like yours usually require immediate help with a psychologist or psychiatrist to help you improve your mental health. Talk to your doctor about referral. Meanwhile it is important to balance our lives with the demands put on them. Techniques to maintain balance in our lives include physical exercise, a healthy diet, avoid alcohol, smoking and drugs. Gettng help is essential.
Stress reduction. The most immediate thing to do is to learn simple relaxation skills, which you apply throughout the day, even a few seconds at a time. There are very easy practices that pay attention to your breath that are very effective in calming us all down. For example, look at this: https://www.Youtube.Com/watch?V=8-_nncrrdus besides these, there are many easy-to-learn stress managment tools available.