My 3rd was an unplanned pregnancy. I had a 3 yr old and a 17 mths old toddler that time. I was also on family planning. Stopped for a while due to massive terrible migraine which was the side effect of the pill and got to know I fell pregnant the next mth. Like you, I wasn't ready to have another child. Furthermore my toddler was very clingy & likes to cry. I developed pregnancy blues and constantly scolding my poor toddler who knows nothing. My husband does noticed my sudden changes & helped out as much as he can. We put our children at their grandparents whenever I feel like I needed to rest. After I gave birth, I regret feeling not ready and the times that I badly treated my toddler. I wished I could really turn back the time and embrace everything. Now after 10 yrs, I'm pregnant again. But this time, I am all set and ready. My children are very close to me and they can't wait for their new baby sibling to arrive soon. Love my children with all my heart. Talk to your husband about how you feel. If you ever need any help, do not hesitate or shy to ask. It really helps.
My 3rd was unplanned and my 1st is 18yo and 2nd 13yo. While I did dread that I have to go through it all over again, I simply couldn't bear to give up. However, everyone is different in handling such situation and there's no right or wrong. You need to weigh out the options and talk to your family member about it. Family support is very important and will help you decide on what's best. All the best.