Losing my therapist, this is the 2nd time. How do I cope?

First, let yourself feel the loss. It’s okay to be upset and to mourn your therapist leaving. Recognize that you were ready to open up and that this is genuinely hard.
Write down everything you’d want a new therapist to know or address.
Reach out to the clinic for guidance. Let them know you’re not ready to jump into a new therapist right away, and if they push, be firm, this is their job: to support your mental health.
Lean on support outside of therapy, like trusted friends, journaling, or grounding exercises, to help you through this transition while you wait to build trust with someone new.

@ehdog Have your final sessions with your therapist focused on her leaving and ending therapy with her? This is a transition that should be part of your final sessions. Have you talked about who she thinks you would work well with? Since the two of you have a established a strong therapeutic relationship she should have suggestions on who you can see in the future.

This is difficult. It has happened to me. From both a clinical and ethical standpoint she should be providing you with referrals. Has she done that?

I agree with @naturegirl15. There needs to be a session to process the relationship and therapy ending. I would ask her if she knows of another therapist she can recommend. I know it is difficult after building trust with someone and then the therapy has to stop for whatever reason. Just know that there is someone else out there for you. I know that I lost my psychologist years ago and it was difficult, but I have since found a therapist that I am working with and it has helped me more. So, I know that at this time it is difficult to see but something better may happen. That seems to be the way things go.

Been there, done that - sucks completely. I’m a survivor of sexual abuse, so trust is really hard for me as well. I had the same therapist for over 7 years, and then she retired. While I was happy for her, I was devastated for me. We were at a critical point of my therapy, having made some crucial breakthroughs, when she left. I had to face basically starting over with a virtual stranger. Most new therapists want to basically have you go through all the details again - almost a total reset of the process. It took me almost 18 months to trust her, because I now worry that she’ll leave too. I feel badly for you and will be praying that the new therapist sticks with you. Before starting with the new therapist I’d suggest you do a dive into the reviews online of your current practice. There could be a significant reason for the turnover rate in that practice. I will be praying for you.

Do you know why she is leaving? Can you comfortably ask? Does the clinic you go to have a reputation for frequent turnovers? If yes, then maybe you can find a place that is better able to hold onto their staff. Some places are "proving grounds" for brand new people, causing them to move on once they have become "established". (I am in the process of establishing a new relationship with a different form of provider and my plan is to ask him how much he already knows about me, let him know knowledgeable I already am about my condition, tell him I am hoping [a veiled way of saying "I EXPECT ] we can work together as a team, politely giving him a warning that I have been gaslit before and won't allow it to happen again.) Medical care is a business deal.
It looks like you will have to shop around again and again until you find someone you can trust and make sure they know you already have trust issues. If you stay at the same clinic they should have enough records for any new provider to review. Ask your new therapist if they have a long term contract and if they plan to stay put. Take charge at the first session. Rip off the bandaid, if you can, and spill out everything traumatic you have already told your former therapist as quickly as you possibly can - get it over with. You've already done it with the two previous therapists so you can do it again. Maybe the new one will be the best one ever. Don't waste any time doing the delicate dance of becoming "friends". You have nothing to lose by spilling your guts at the get go. You will need to work from your gut and it will be hard but getting it over, quickly, will help to establish a new relationship - their response will be the indicator as to whether or not they are right for you. Be firm and advocate for yourself, but by advocating I don't mean being harsh, bullying, demanding or rude. As you already know, its a symbiotic relationship where you have to trust and respect each other in order to work together.