Transition from DLA to PIP - very anxious

I am in the process of transferring from DLA to PIP (I hope). I currently get the lower rates of both DLA components, because of my long-term depression and anxiety. Part of the depression and anxiety is caused by my husband, who suffers from bipolar affective disorder, PTSD, OCD and dyslexia. I am his carer, and every day can be very stressful for me because of my husband's unpredictable behaviour. 11 years ago I was bullied at work by another colleague, and suffered a breakdown (layman's term, I know) as a result. I went back to work, and was then bullied by my manager, resulting in another breakdown. The company denied any wrongdoing (what a surprise) and subsequently made me redundant. I was too ill to fight this, and in any case had decided I couldn’t return there even if well again. The redundancy payment enabled me to start a small book publishing business run from home, which meant I could be there to care for my husband, whose condition had worsened. The business is very small and 2017-2018 is the first year it has made a (very small) profit. The great thing about it is that I can work whatever hours I like, at times when I feel well enough to do so; although I am now in receipt of the state retirement pension I have carried on with the business because, without it, I think I would go out of my mind – my husband’s CPN said recently that it was my ‘therapy’.
What I am afraid of is that the claim assessor and the DWP will decide that if I can run a business I don’t need PIP, which is simply not the case. I have problems talking to people face to face or even on the telephone and because of this my business is carried on exclusively online. I rarely go out unless I absolutely have to, and most of my shopping is done online. As I said above, my business is my lifeline – as the CPN said, my ‘therapy’. Can anyone give me any advice as to how to deal with this aspect of my claim? Any advice would be very much appreciated.