You are asking among the most common and, for some people, the most troublesome and uncertain of all questions about HPV. The answers are complex and fall in the realm of personal judgment and ethics more than science. There are no hard and fast rules. As it happens, within the past week I have addressed exactly these issues in great detail, so my comments below are brief. Please read the following three threads:
http://www.medhelp.org/posts/show/763292
http://www.medhelp.org/posts/show/763984
http://www.medhelp.org/posts/show/761416
The quick replies are that even if you were the source of your ex's HPV infection, you may no longer be infected. Most infections go away in a few months, so you aren't necessarily going to transmit it again. Further, virtually any partner you're likely to meet, and most partners you have had in the past, have been infected with HPV before and likely will catch it again. Getting HPV, including the high risk types (which are the most common types), is a normal and expected consequence of human sexuality.
For these reasons CDC and most experts believe it is not automatically necessary to inform past or future partners when HPV is diagnosed or suspected. But other people disagree. Also, the nature of a relationship might be important. In a potentially long-term, committed relationship, often it's better to discuss past HPV and other STDs early on, to avoid the risk of a more difficult conversation if the partner develops an abnormal pap smear, genital warts, etc.
The threads I recommended above go into these issues in great detail. Please read them and then feel free to return with a brief follow-up if something isn't clear. Also, you might visit MedHelp's HPV community forum. You will get lots of opinions on all sides of these issues.
I hope this helps. Best wishes-- HHH, MD