If you have had an abortion, you can continue measuring your temperature to stay in the routine of measuring. The algorithm will take the pregnancy and temperatures into account.
If you are not sure how to let the app know that you are no longer pregnant, kindly have a look at this article on the subject.
The bleeding you experience after an abortion is not your natural period. You can either log this bleeding as 'period' or 'spotting' in the app as the algorithm will adjust accordingly. The first bleeding after your ovulation is your period and should, of course, be logged as a period.
You can expect more red days in the beginning, as the cycle may be irregular for some time, but this will even out in time. Just keep measuring your temperature often - aim for 5 'Normal' temperatures per week.
In any case, we can understand that going through such an experience may be very difficult emotionally and physically, so do not hesitate to contact our support team if you need any additional assistance.