Am I capable of doing PhD based on my advisor's words?
Though I can't relate to your situation, I have friends who were in a similar situation during their Ph.D. They were mentally abused and constantly demeaned by their advisors. Though this behaviour is predominant in South Asian universities. But it's quite prevalent in many western universities too. However, all my friends who went through such hard times, they did one common thing, they persevered.
They did not lose hope and did whatever was necessary to get the degree. After they graduated, they went their own way and are leading happy lives years after graduating.
What I trying to say is, you know that you are hard-working and a good student. What you are going through is because of your circumstances. You have worked hard for the past 4.5 years on your Ph.D., don't lose hope now. Do what's required for being eligible to defend and then change your circumstances.
All these let me to realize that I actually not capable enough mentally and emotionally to be successful in PhD or even in any job from now on.
Don't focus on something that hasn't happened yet. Your job now is to complete your degree. Don't worry about the success and job at the moment. Those will come. You are capable, that's why you are in a grad school.
Should I conclude that I am not capable enough to do PhD with the words of my advisor? or Should I give myself another chance?
No you shouldn't conclude that you are incapable of doing a PhD. Whether or not you should give yourself another chance depends entirely on you. We can help you with identifying the salient points that should play a role in that decision. (More on this later)
Overall, I am not blaming my advisor
That shows that you are mature and capable of being critical of yourself. But your supervisor was abusive. That behavior you described is not normal and it should not take place anywhere, let alone a university. Your supervisor has a lot to be blamed of, keep that in mind.
All lead to depression and anxiety.
That is understandable. But please don't overlook this. We (or at least I) are not qualified to give you advice on how to deal with depression. But I can suggest you to go see a medical professional. Health, and in this particular case mental health, is important above all.
What options do I have?
It greatly depends on the university. In my university for example we have a "mentor," which is a professor assigned to you who checks in on you periodically and acts as a neutral party when you have problems.
For instance, I could go to my mentor and tell him "look, my supervisor is being abusive. Am I crazy or am I right? What can we do?" And he might suggest to change advisor, mediate the conflict etc...
Maybe you don't have such a figure. In another university we had a similar figure but it was more general, not assigned to you personally. Check if your university has such a thing and do go talk to them.
If not, you could consider changing supervisor. That of course depends on various things
- How far along in your thesis you are. If you are almost done, it's probably not worth it.
- Is your supervisor an influential professor in your department, or is s/he generally admired? In that case your next supervisor might resent you for the choice you made.
You might also consider changing university altogether but that would likely mean starting from scratch. Fresh starts are good, but also very energy consuming.
Given what you described, it seems that your supervisor is breaking ethical rules that nearly any university would have. You may look at the appropriate department in your university and seek to file a complaint. This is an action that you could take together with one of the previous two suggestions.
Finally you could also hang in there, hope to get a decent letter and start a postdoc in a better place. However you should check that your anxiety allows you to do this. If the situation becomes unbearable, don't try to resist it.
Should I continue academia?
Like I said, we are not going to make a decision for you, but consider these
- Do you still love doing research and, in particular, do you love your particular area of research?
- Would you like to teach at university level?
- Do you believe that in a more supportive and encouraging environment you would be able to perform better?
- Are there any other jobs that you would consider doing other than academia?
- Have you taken under consideration alternative options, like leaving academia and returning at a later moment.¹
Answer to (not necessarily only) these questions sincerely to yourself and decide accordingly.
¹ Gaps in the resume might be hard to motivate and might get in the way of getting a job in academia after having left it. But, even though I cannot provide any examples from my experience, I don't think that it would be absolutely impossible to re-enter.