Should I admit that I was a first-year PhD student in future interviews?

It is typical in applying for a job, graduate program, etc, to account for how you've spent your past time. If you are an undergraduate student for some years, then maybe a master's student, and then there is a gap in your resume from when you were a PhD student, it will jump out at anyone reviewing your application.

It doesn't look good that you've left your program, but it looks worse if you have no answer for how you spent that time, and worst of all if it becomes clear you intended to mask your time as a previous grad student.

No matter how you go about this, it looks bad that you did not complete a PhD program. Applicants for a PhD are assessed primarily based on their perceived likelihood to be a successful PhD student. As a past unsuccessful PhD student, that perceived likelihood decreases, especially if your past PI says bad things about you and people believe them.

In the short term, you likely need to gather some new references. You need people who can vouch for your ability and potential as a researcher. Depending on your field, the availability of such positions may be limited, but in my own field I would advise taking up employment in an academic lab as a technician. The barrier to entry is much less than for a PhD position where an institution is dedicating themselves to you over several years. Your PI in that lab will be able to recommend you to programs that you subsequently apply to, and confirm to them that your prior experience was a fluke.

You asked for candid advice, and I am doing my best to give it. If I was reviewing your application, and saw that you left a PhD program after a year, I would not want to take you on as a student. Regardless of whose fault it is, there are many many qualified candidates for most PhD programs. If you got grants and publications, that may help, but you still have clearly had a personal conflict with your past PI and have accused them of many bad things. The last thing I would want would be to take you on as a student, bright as you may be, and then be accused of similar things myself. I wouldn't have any objective information to assess whether you are a victim as you claim or not, unless someone else, whose input I trust, gives me information about the situation.

In addition to Bryan's excellent answer, it should be noted that depending on the policies of the school you are applying to, omitting details of attending a previous PhD program from your application can be considered sufficient grounds to revoke offers of admission. Therefore, if you are directly asked about your past experience, you should not attempt to lie about it, either directly or by omission.