Sorry that you are feeling low.
You will get over it fairly quickly and stop yourself sinking into a full depression if you stick to a few simple principles.
First: do get out of bed each day at a regular reasonably early time. Try to eat regular nourishing meals even if you don’t really feel like it. Wash and clean your teeth. This will stimulate your system. Go to bed at a regular reasonable time that means you’ll get about 8 hours sleep. Getting your body clock into a routine will help your mind adjust and stop you from getting into a full depression.
Second: Keep active even if you don’t feel like it. Act as if you felt like it at first, and soon you will. Choose things to do that you will enjoy. Don’t sit and watch TV. Being a passive recipient will leave you time to brood. A film is better than TV if you want to sit and watch something for a bit, because you are likely to be more engaged. Aim to do something active each day.
Third: Talk about how you feel and what is bothering you to a friend. Listen to their response, and then let it go. Don’t keep thinking about it. This is called rumination and will make you feel worse. If only’s and self reproach will not help. If there are lessons to be learned from what has happened then make a vow to yourself that “next time I’ll …..” and then let it go.
If you want to know more about this then read https://www.life-goals.co.uk/natural-ways-…