This is a long post but I really need advice-

One of my best friends met a girl last summer online while he was living in a different country. They dated for a month and a half and then he moved back to the US. Since then, he's visited her a couple of times, but mostly they communicate via text. She has borderline personality disorder and becomes very emotionally dysregulated and even abusive at times. They talk literally nonstop all day and if he lags in response time, she freaks out and accuses him of cheating and becomes very mean to him. They have broken up three times in the past year due to this behavior. Two months ago he ended things because she was very insulting to him (he was attacked and robber and she told him it was because he was weak and she didnt want to date a cry baby). She threatened suicide and texted him hundreds of times a day begging for him to take her back. My husband and I were big supports for him during this time. Two weeks after the breakup we found out they had gotten back together but he was keeping it a secret from us. We both expressed our concerns to him that she is abusive and unstable but let him know that ultimately he is our friend and we want him to make his own choices and be happy (we did not want him to feel judged or like he had to hide things from us). Since then he has not really mentioned her. We found out, out of the blue yesterday from a Facebook post that they are now engaged and have been for a week and he is moving her (and her 8 year old son) to the united states. He does not currently have his own house or a job. I am shocked. We literally had dinner with him two days ago and he did not mention ANY of this. I texted him asking if it was true and he said it was and he had wanted to tell me in person instead of text, which is odd since he had already posted it on FB. I responded that i wanted to be happy for him but that I also felt concerned as it felt like he was trying to hide these things and it made me confused and worried for him. He is now ignoring me and my husband thinks my reponse was too direct and judgemental- am i wrong here? I feel like ommiting the fact that you are engaged to your best friends but positing it on fb is very weird, not to mention the fact that becoming a stepfather and getting married to someone you just got back together with recently seems really really impulsive....