Firstly I find it extremely worrisome that these people even have the power to make you feel suicidal. I mean, I would completely understand if it was someone close to you, but its his friends...
So I'm actually at a loss there, but would suggest you reclaim your power, it has no business being in someone else's hands anyway.

Secondly, communication is key in any relationship, and when its lacking in a romantic relationship, allll sorts of shyt ends up hitting the fan.

If the 2 of you can't talk about the hard stuff now, it will only get worse during marriage, so if you can't find a way to communicate effectively on your own, I suggest couple's therapy.

Last but not least, I myself would feel gutted if my bf did not stand up for me if the situation called for it (such as you've described here) but that would probably be more because I know it would be very much out of character for him not to do so, and thus reflect badly on his feelings for me and our relationship.

My BIL on the other hand is very non-confrontational, he hardly stands up for my sister, figures she can fight her own battles without him running interference and making things even more awkward. She has struggled a lot with this in the past (inlaws and friends etc) but she admits that as much as it has hurt at times, she knows he's just trying to keep the peace and letting everyone sort out their own shyt.

On a side note, if these friends have always been good friends to him, it may be worth it to figure out exactly why they hate you. I'm not saying that there must be some type of blame placed upon you here, but generally good friends want what's best for eachother and if they're under the impression you're anything less than best for him, its worth investigating and addressing.

i.e What are their feelings based on, where did they get their information, and then work it out among eachother from there.

Just some food for thought