The mortgage is ignored.
You bought it for €117k. You would have had some allowable acquisition costs (e.g. legals, stamp duty perhaps, etc). Let's say they augment the total to €125k.
Then there is some indexation of the €125k, but only until 2003. There's a special table setting out the relevant numbers (just Google "capital gains tax multipliers indexation").
Then any big enhancement work can also be included (and indexed if relevant). But let's assume there's none.
Then you sell it for €180k and let's say you incur allowable selling costs of €5k.
So overall, a gain of circa €50k (ignoring indexation).
It was your home for 13 years out of 18 years. An extra year of deemed residence is then added. So 4/18 x €50,000 ends up being subject to CGT. That's €11,000, less your €2,540 allowance, so €8,500 taxed at 33%, meaning €2,800 of tax payable (assuming neither of you have capital losses).
Back of the envelope stuff, so caveat emptor, but you have the bare bones there...