You hardly need software to do that. Any simple scripting language can do it. In Python it would be only a few lines. You can do this in a complex way, but even if you just replace every ">" with ">\n" then you will be fine:
In Python (which you may have on your system anyway...if you have linux or mac - just go to the command line and type 'python') you could do this:
>>>r = open('/path/to/yr/file.htm', 'r')
>>>toParse = r.read()
>>>r.close()
>>>import re
>>>wasParsed = re.sub(">", ">\n", toParse)
>>>w = open('path/to/yr/file.htm', 'w')
>>>for i in wasParsed: w.write(i)
>>>w.close()
That's it. It could be done better, and you don't even really need regular expression. But doing this is so simple and you would save yourself installing something. If you have Python and want to try it, you could write to a second file just to test, before committing it finally. If you have any trouble, there are so many good Python forums, such as the one on Daniweb.com
I just show Python code so that you can do it even if you don't know any scripting language, but you can see that it's a really operation, and can be done a whole lot better if you do have a scripting language.