Ex's mom texting me

So my bf broke up with me 3 weeks ago and I finally blocked him for now but yesterday his mother messaged me on messenger and I just left her on read. This whole breakup has put a lot of stress on me and I'm having to take antidepressants now (also trying to get a therapist) because I've been feeling very depressed since the breakup because I really love him and it's been a lot not to mention being 31 weeks pregnant on top of it. His mom is a very sweet lady and feels sympathy for me but last week she kept talking about the breakup and my ex and it brought me to tears and I honestly don't want to talk to her right now as I'm trying to get myself mentally stable again and deal with all my emotions (I'm doing better then I was the first 2 week's). My question is would I be considered rude if I didn't talk to her right now?