Hi BPD redditors,

I'm not exactly sure how to put this or where to start. Throwaway for obvious reasons.

I'm so stupid.

I met my current girlfriend over a discord server last year December. It was fun hanging out and chilling with her and showing her films and tv shows she didn't know about and generally really good.  
Over time as we got to know each other more deeply it became more and more apparent she didn't have anyone to depend on or that she fully trusted to tell everything to. 

She is incredibly caring and loves animals, she dislikes watching them get hurt (even if its surgeries to help). 

I on the other hand tend to be detached and apathetic to most things. The one thing I care most right now is her and her wellbeing.

Please note that through the course of several months (i suppose half a year) we had been seeing each other (admittedly it's online, but i doubt it matters that much nowadays). 

Both of us are about 8000km (5000miles) apart from each other, and due to COVID we haven't had much luck of meeting each other in real life. I was planning on asking her to be my gf irl but yeah, COVID. She did have anxiety issues with not being with me officially, and she was really trying to not push it which I was thankful for. But one day after a long while of being in the unofficially going out stage, she used logic and I realised it's for the best and I asked her to be my girlfriend which she agreed.

I'm assuming I had some deep seated reluctance before to be in a relationship because as soon as that happened, I became more happy (I guess you could say mania too) and way more sexual. And this is where the major f\*\*\* up happens and I proverbially open a s\*\*tcan of worms for the both of us.

I had joined a gym to exhaust my now boundless amounts of testosterone. I got shoulder and back pain. I booked a massage at a massage parlour, it was seedy af. I had every opportunity to cancel and still went there. I won't go into the details because I still feel guilt and shame about it but yes, I cheated on her with the masseuse.

I remember vividly the day after realising what I had done, and I had a panic attack. Every day I racked it in my head whether to tell her or not cause it would hurt her so much or to not tell her and hide the truth. I tried to figure out the best time to tell her but there really was no good time. 

I told her the Wednesday after. I cried, a lot. Out of guilt, shame and sadness that I caused her so much unnecessary hurt. I haven't cried so much in a while. And then the stages of grief came and hit her. At which stage I'm not sure anymore but it opened a can of worms that:

I : possibly bipolar(I definitely have bouts of depression), sex addict + ADHD - I've reached out to the Doctors and looking into an official diagnosis

She : We both suspect she has BPD, but she isn't receiving treatment. It's really opened up everything in the open between us.

As most of you guys will know, BPD sufferers have problems with abandonment and anxiety/paranoia. 

Because of me cheating, I've lost all trust in her (rightfully so tbh). At this point in time she doesn't like feeling anxiety and paranoid about wondering where I am and what I'm doing or where I'm going with, and it's understandable.

At this point we're fighting everyday, and if we're not its the weird calm or she is disassociating with me. This whole thing has been difficult for the both of us.

We're looking at reconciling the relationship between us and working through it, it's still fresh wounds and it's really hard. We've agreed to start an online couples counselling which I hope will help and we're looking into that.

I think what I find the most difficult is the fact the one person she relies on, cheated on her and broke that trust.

Her current coping mechanisms with what I've done are chain vaping and drinking alcohol everyday after work and when she's off.

My coping mechanisms tended to be m\*\*\*\*\*bating and hanging out with friends . I don't m\*\*\*\*\*bate now cause of the aforementioned sex addiction, and I don't hang out with my friends currently cause I want to rebuild the trust and help her feel less paranoid and anxious about me potentially cheating again. I've assured her I won't but it's hard to rebuild that trust. 

I've bought a few books on BPD and how to be a supportive partner. I've barely started the first book I bought but it's been helpful understanding mood swings.

Sometimes I wonder if space is required for us to heal, but as I'm solely the person she confides everything with and given the suspected BPD, I've found it difficult. I'm looking at alternative ways of coping myself cause it's mentioned many times to make sure the supporter is mentally 100%, but I don't know any aside from meditation.

She needs help, I need help. What can I do to make it easier on her?  What can I do to help make her less paranoid and anxious, but also ensure that she doesn't think I completely abandon her? Essentially, how do I rebuild that trust?

Apologies for the long post, I'm not even sure if it's coherent but I tried.

TL;DR: I cheated on gf. During relationship we opened Pandora's Box and we realised I might have sex addiction + bipolar and she might have BPD, what can I do to help her?