knock m-i-l down. use laptop to take out potential gun holder. slam door dial 911.
you'd be on the "gun puller" faster then he would have time to react. especially him being focused on boyfriend.
either way the m-i-l should be "talked to" for putting you in that scenario.
like say by her neck..... IMHO
but realisticaly with 'friends" like she has. you'd act and have her jump on you for interfering. that by the neck sounds even better now!
then i'd suggets she by one where the chance of it being hot are somewhat less