Hello, this sounds like a very difficult experience to be going through. Relationships can become a very big part of your life. To go from sharing a big part of your life with someone to suddenly not being able to depend on them is a very big transition to make. Moving on from such a relationship is a very big change to make. This may even take you some time. We, as humans, can grieve over the loss of most anything important to us, including the ending of relationships. It sounds like you may also be grieving over the loss of your relationship.
Grief tends to occur in stages. It begins with denial or difficulty in coming to accept that something has happened. At some point, the experience brings up feelings of anger, of wishing it hadn't happened with you, and at times, even intense sadness. This is a very normal process and it is okay for you to be feeling this way. At some stage, a person who is in grief reaches the stage of acceptance. Break-ups are extremely difficult, I hear you. Allow yourself some time and self-care and you will eventually reach that stage of acceptance.
Next Steps
I would recommend that you approach a therapist! Seeing a therapist may allow you to process all these big feelings. Therapy can even help you process the grief, the ending of the relationship, the sudden transition you are having to make and all the feelings it is bringing up for you. Through therapy, you may also be able to identify some ways to help you cope with all that you are going through.
Health Tips
For the meantime, you can continue to moderately use activities such as exercise to help you cope and care for yourself. Alternatively you can try, 1. Creative outlets such as art, music, drama, dance and so on. 2. Journalling may help you reflect and express yourself. You can either use structured journaling prompts that you find online or simply write of whatever feels natural to you in that moment. 3. If it is safe and possible for you at present, meeting some friends or family may also help! 4. Of the biggest forms of self-care, is therapy. Please do consider reaching out to a therapist!