If this wasn't the area of law I practice in, I would read threads like this and think the OP was making things up as they went along (there have been several threads like this over the past few days).
My initial post stands, it is very unlikely that the court will refuse to take your ex's statement. Your solicitor is certainly right that she can challenge its admittance, but if your ex is a litigant in person, the court will almost certainly allow it, to ensure that your ex feels that he had a fair hearing (a human right).
You are clearly concerned because you know that you lied in your statement, and his further statement and evidence will prove that. That doesn't look good for you. You claim he is a neglectful parent, but the evidence from contact is showing that he has a good relationship with the child and that she enjoys the contact. It is likely that the s7 report will support ongoing contact, probably in the community, perhaps overnight (depending on the age of your child), and this may or may not be over a phased period of time so that your child can get used to it.
This is not about you 'letting/allowing him have contact', the court will make the order and you will have to follow it or face possible sanctions - and if you keep ignoring the court order or obstructing contact then the courts can ultimately change residence of your child. Your solicitor should have told you all this. Your solicitor should also have told you that lying in a witness statement will not bode well for you.
The court can order whatever it likes at this juncture, though the usual outcome is every other weekend, a day in the other week and half the holidays - with all special events shared 50/50. If he asks for alternate Christmases, it is likely he will get them. You say that would be unfair on your other daughter - well, he has a child with someone else, so it would be unfair on that child if they never got to spend Christmas with their older sibling. It works both ways.