The other parties will always make a counter allegation if the police are involved. the sad fact is, you cannot prove you did nothing, unless police can do house to house/check cctv of the area etc. The child would not be a reliable witness and therefore would not be credible if the case went to court. The real story may never be told by the other party and there is no way to prove that you did not retalliate, even if you didn't the first or second time.
If the police were involved the first time, the case would have been classified by the seriousness of your injuries and the assaults. then the CPS would have been consulted and they make the decision on whether it is in the publics interest to go ahead with a case in court.
I would advise you to find out if they can be warned under the harrassment act by the police - if they then contact you or continue to harrass you by any means, they can be arrested. You could even speak to a solicitor or citizens advice about getting an injunction against them. And try to avoid them at all costs but report any incident to the police so that they have a record incase this matter goes to court. Hope this helps