The 26-year-old had an operation after breaking the radial bone in his arm when three explosions went off as the bus made its way to the stadium shortly before Dortmund's Champions League clash with AS Monaco.
"The pain, the panic, and the uncertainty of not knowing what was going on, nor how long it would last... they were the longest and hardest 15 minutes of my life," the Spain international wrote on Instagram on Friday.
“About all of that I want to tell you that I think the shock of those days is easing all the time and the desire to live, struggle, work ... play (and) train ... is getting stronger."
"What do I feel when I look at my swollen and badly damaged wrist? I feel pride, thinking that all the harm they wanted to do to us on Tuesday led to nothing worse than that."
The accompanying photo showed Bartra looking towards his family. He had a cast on most of his right arm and around his left wrist.
Dortmund said on Thursday that Bartra, who joined the club for €8 million from Barcelona at the start of the season, should return to playing in "about four weeks".
Tuesday's match was rescheduled for 24 hours later and Monaco secured a 3-2 victory over Dortmund, who will next host Eintracht Frankfurt in the Bundesliga on Saturday.
Read the full article on eurosport.co.uk: Dortmund blasts the 'hardest 15 minutes' of Bartra's life