Stressed

I’m going through so much right now my husband left me 3 weeks ago and I’m 16 weeks pregnant and he won’t stop texting me about how the baby isn’t his and that I just need to give him the baby because he can raise it better then me need to remind everyone that I’m 23 years old and I’m in med school and I work full time

I have a 7year old son & a 1 year old daughter and this baby on the way he says becasue I’m too busy with work and school and that I put that first before him that I won’t raise my kids right ugh idk what to do ...... also he’s 45 years old and thinks I’m not able to take care of my babies when I work no. Stop and go to school ugh I’m so stressed out I’m in need of great advice ....