Welcome to the forums. I'd like to commend you on your courage for posting on the forums about your troubles. Your message will help reach out to others who may relate to your story, and helps make them feel that they are not alone.
I can resonate with your feelings of being the strong one. It is the sense of needing to be perfect in order to gain approval from another person. The sense of not showing any vulnerabilities to appear strong so others know we are someone dependable and competent. The problem with that is, the more we hide our vulnerabilities, the harder it becomes to maintain that composure. Eventually it'll become a really heavy burden to carry, that we'll one day burst/breakdown/crumble, and that is very detrimental to our mental health.
It's okay to allow yourself to be vulnerable to others. It's okay to tell others that you're not ok, to call out your boundaries that you cannot do it, to call it a day and say "I'm tired today, but I will try again tomorrow". Your needs are the most important to yourself, and we can only begin to be selfless and contributing back to the community when we're comfortable with our basic needs. Taking care of your basic needs first isn't a sign of selfish, rather it's a sign of self-love. We need as much self-love as we can in order to continue growing; to accept our weaknesses, and appreciate our strengths, know our wants and needs, while knowing what turns us off.
If I understood correctly, when you mentioned "there is no-one to be strong for anymore, I don't know how to carry on." Do you feel the need to prove yourself worthy to others? To gain the approval and acceptance of your identity, through another person's approval? And if you don't mind me asking, as I'd like to understand you more, what made you feel that you had to avoid people, and get panicky at the thought of bumping into someone? You don't have to answer any of the questions if you don't feel like it, but I'm happy to listen to you more if you'd like to share more :). You're not alone Jtaime!