his ex is our neighbor

..... yep, you read right.

my boyfriends ex is our freaking neighbor. i thought i seen her the other day and i guess i was right, they finally moved in and shesour neighbor. my bf is out of town working for 3 days and i need to collect myself before he comes because i'm livid, i'm shaking and idk what to do or say . PLEASE HELPPPPP. give me advice i'm literally dying inside

update: sorry i didn't post enough information.... i had just seen her and i was obviously mad lmao. but my problem is that i will insert a pic of the houses, but we just bought a duplex through the habitat for humanity organization (helps out first time home buyers) we have one side of the duplex and for about 2 weeks now we haven't had any neighbors (the ones we'll share the house / property with ) which i just found out is my bfs ex. she's moving in with her parents so that makes the situation a little worse because who knows if she's in a committed relationship, who knows if she still has feelings for him or him for her (he can tell me no, but doesn't mean it's the whole truth) i've seen her before and she's completely avoided me one on one, but will try so hard to get his attention when we've seen her around while we're both together. me and him have a baby together and a while 5 years together. i'm already insecure as it is and literally just dying inside... what if they still have feelings or something or what if one day i'm not home and they get to talking ? and call me insecure or whatever but NO i would NOT be okay with them ever exchanging words. ever.

we share one of these, not our house but across the street but they're all the exact same .