How can I finish my PhD?
Do not get distracted and focus on completing a thesis rather than publishing. After 10 years, you should have enough material to write a decent thesis, even though what you have done may not be publishable. Get support from your supervisor and anyone supportive from the your department to achieve this. Otherwise, self-fund or reach out for coaches or mentors are able to achieve this aim. Ideally people that know your area and can help support you to focus on your thesis rather than the publications. 

I understand and respect that publication is important especially in mathematics. Publications is the focus for an academic career but you have already invested 10 years of your life and it does not sound like you are going to be hitting a string of publications soon. Also, if you are already working part-time, it seems to me, getting the PhD and then working full-time is a very reasonable and respectable career goal. 

Recognise that you get a high every time there is a new challenge. Every one does. It is far more exciting to mov from one exciting topic to the next. Every new challenge has a buzz to it. You have to decide whether this buzz and excitement is more important than completing your PhD. Going over old material and old "stuff" would be drudgery and probably your previous traumatic experience (as you remember why you were not able to achieve publication), but it is important to swallow your pride and decide whether completing a thesis and your PhD is more important than achieving the goal of publication.