I have mrsa hives on arms and legs, back and now a ulcerated one on my vagina lip how likely is it that ill get sepsis?

MRSA treatment: Sepsis can occur but is less likely to happen if you get treated. Mrsa infections are usually treated with antibiotics. People with recurrent infections sometimes need decolonization. Chlorhexidine is a soap that can be used to decrease the load of MRSA on the skin and decrease risk of infections and sepsis. You should ask your doctor if this would be a good option for you.

Low, but get treated: If you have multiple abscesses on your skin including one that is open/ulcerated and are not yet septic i would say that the odd of sepsis for you are low. However, treating these is essential for two reasons - you don't seem to be ridding yourself of them, and they are contagious.