If you confess giving three talaqs, your wife was divorced with three irrevocable talaqs whether there was any witness or not. After pronouncing three talaqs, you cannot take her back. However, if you want to take your wife back, then after passing her iddah (if she is pregnant then after giving birth , otherwise after passing three maturation) she should marry to someone and they have sexual relationship. I Now, if the second husband gives her talaq by consent or he passes away, she, having passed iddah period, can marry you. There is no other solution available for that.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband