My best friend is getting married in June and her fiancé has A LOT of red flags.

Some back story about him:

(We'll call him Stuart)

He's a recovering meth addict.

He has many DUIs (to the point where he can't drive their car and had his license taken away, he has recently gotten his G2 again)

He's an alcoholic (has not admitted to it but has disclosed with my fiancé that he takes caffeine pills so he can stay up and drink).

Some backstory about her:

(We'll call her Dawn)

Dawn's father and mother divorced because he didn't love her anymore.

He had cheated on her on multiple occasions (which has been heavily implied but never stated).

Her step dad was emotionally abusive, an alcoholic and had cheated on her mother, they have recently divorced.

Dawn has a bad history of dating men who are cheaters and that gaslight.

So 3 years ago, Dawn met Stuart on Tinder.

Within the first month of their relationship he got into a fight with his roommate and was arrested for battery after he had knocked the guys teeth out.

While Dawn was at a musical festival with her friends, Stuart brought a girl home and cheated, he swears it was only oral, this was around their 8th month of dating.

Last year while Dawn, her mother and his mother were away on a trip, he got drunk and decided to go to Toronto where he did Meth.

About 6 months ago, he had broken their shower and told her that it was her fault then told her he hated her.

He had been drunk, had fallen asleep and apparently this can happen

He is currently upset with Dawn as she changed the Groomsmen's suits to one that is not only cheaper but is also purchasable as my fiancé had chosen to purchase his suit.

He did not realize that the suits had been changed when she showed him the photos of the suits.

Stuart will also start fights saying that she's cheating because socks and spoons have appeared randomly in their apartment.

Our mutual friend and I have decided to confront her about our concerns about him but we don't know how to start or how any of this is going to go down.

I am her maid of honour and she is mine, our Fiancé's are also really good friends.

If anyone has tips it would be really helpful.